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822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 130CFX-5 Tutorials Page 257
Master Contents Master Index Help On Help
CFX-5 Tutorials
Tutorial 12
Flow in an AxialRotorStator
Sample files used in this tutorial can be copied to your working
directory from ltCFXROOTgtexamples SeeWorking Directory (p 2)
and Sample Files (p 3) for more information
Sample files referenced by this tutorial include
bull Axialpre
bull AxialInipre
bull AxialIni_001res
bull statordef bull rotorgrd
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Flow in an Axial RotorStatormdashIntroduction
Page 258 CFX-5 Tutorials
Master Contents Master Index Help On Help
12A Introduction
12A1 Features explored in this tutorial
Introduction This tutorial addresses the following features of CFX-5
Component Feature Details
CFX-Pre User Mode Turbo Wizard
Simulation Type Steady State
Transient
Fluid Type Ideal Gas
Domain Type Multiple Domain
Rotating Frame of
Reference
Turbulence Model k-Epsilon
Heat Transfer Total EnergyBoundary Conditions Inlet (Subsonic)
Outlet (Subsonic)
Wall No-Slip
Wall Adiabatic
Domain Interfaces Frozen Rotor
Periodic
Transient Rotor Stator
Timestep Physical Timescale
Transient Example
Transient Results File
CFX-Solver Manager Restart
Parallel Processing
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Flow in an Axial RotorStatormdashIntroduction
CFX-5 Tutorials Page 259
Master Contents Master Index Help On Help
You learn about
bull using the Turbo Wizard in CFX-Pre to quickly specify a turbomachineryapplication
bull multiple Frames of Reference and Generalised Grid Interface
bull using a Frozen Rotor interface between the rotor and stator domains
bull modifying an existing simulation
bull setting up a transient calculation
bull using a Transient Rotor-Stator interface condition to replace a Frozen
Rotor interface
bull creating a transient animation showing domain movement in CFX-Post
12A2 Before beginning this tutorial
Introduction It is necessary that you have a working directory and that
sample files have been copied to that directory This procedure is detailed
in Introduction to the CFX-5 Tutorials on page 1
Unless you review the introductory materials and perform required steps
including setting up a working directory and copying related sample files
the rest of this tutorial may not work correctly It is recommended that you
perform the tasks in Tutorial 1 Tutorial 2 and Tutorial 3 before working with
other tutorials as these three tutorials detail specific procedures that are
simplified in subsequent tutorials
CFX-Post Plots Animation
Isosurface
Surface Group
Turbo Post
Other Changing the Colour
Range
Chart Creation
Instancing Transformation
MPEG Generation
Quantitative Calculation
Timestep Selection
Transient Animation
Component Feature Details
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Flow in an Axial RotorStatormdashIntroduction
Page 260 CFX-5 Tutorials
Master Contents Master Index Help On Help
12A3 Overview of the problem to solve
The following tutorial demonstrates the versatility of GGI and MFR in
CFX-Pre by combining two dissimilar meshes The first mesh to be imported
(the rotor) was created in CFX-TurboGrid This is combined with a second
Definition File mesh (the stator)
The geometry to be modelled consists of a single stator blade passage andtwo rotor blade passages The rotor rotates about the Z axis while the stator
is stationary Periodic boundaries are used to allow only a small section of
the full geometry to be modelled
Figure 1
At the change in reference frame between the rotor and stator twodifferent interface models are considered First a solution is obtained using
a frozen rotor model After viewing the results from this simulation the
CFX-Pre simulation is modified to use a transient rotor-stator interface
model The frozen rotor solution is used as an initial guess for the transient
rotor-stator simulation
Hub
Rotor Blade
Outflow
Shroud
Stator Blade
Inflow
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Flow in an Axial RotorStatormdashIntroduction
CFX-5 Tutorials Page 261
Master Contents Master Index Help On Help
The full geometry contains 60 stator blades and 113 rotor blades To help
you visualise how the modelled geometry fits into the full geometryFigure
1 on page 260 the image shows approximately half of the full geometry
The Inflow and Outflow labels show the location of the modelled section in
Figure 2 on page 261
Figure 2 The modelled geometry contains two rotor blades and one stator blade
This is an approximation to the full geometry since the ratio of rotor blades
to stator blades is close to but not exactly 21 In the stator blade passage a
6deg section is being modelled (360deg 60 blades) while in the rotor blade
passage a 6372deg section is being modelled (2360deg 113 blades) This
produces a pitch ratio at the interface between the stator and rotor of 0942
where the pitch ratio is the area of side 1 divided by the area of side 2 As the
flow crosses the interface it is scaled to allow this type of geometry to be
modelled This results in an approximation of the inflow to the rotorpassage Furthermore the flow across the interface will not appear
continuous due to the scaling applied
The periodic boundary conditions will introduce an additional
approximation since they cannot be periodic when a pitch change occurs
Inflow
Outflow
Axis of Rotation
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Flow in an Axial RotorStatormdashIntroduction
Page 262 CFX-5 Tutorials
Master Contents Master Index Help On Help
You should always try to obtain a pitch ratio as close to 1 as possible in your
model to minimise approximations but this must be weighed against
computational resources A full machine analysis can be performed
(modelling all rotor and stator blades) which will always eliminate any pitch
change but will require significant computational time For this rotorstator
geometry a 14 machine section (28 rotor blades 15 stator blades) would
produce a pitch change of 1009 but this would require a model about 15times larger than in this tutorial example
If you have already completed the frozen rotor part of this tutorial you can
continue from Setting up the Transient Rotor-Stator Calculation (p 276)
Note that a converged results file from the frozen rotor section is required
as an initial guess You can use your own solution or use the results file
provided in the examples directory Further details are given inObtaining a
Solution to the Transient Rotor-Stator Model (p 280) You must make sure
that the boundary names used in the initial results file exactly match those
used in the transient rotor-stator case
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
CFX-5 Tutorials Page 263
Master Contents Master Index Help On Help
12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
Page 264 CFX-5 Tutorials
Master Contents Master Index Help On Help
different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
CFX-5 Tutorials Page 265
Master Contents Master Index Help On Help
13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
Page 266 CFX-5 Tutorials
Master Contents Master Index Help On Help
Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
CFX-5 Tutorials Page 267
Master Contents Master Index Help On Help
2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
Page 268 CFX-5 Tutorials
Master Contents Master Index Help On Help
12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
CFX-5 Tutorials Page 269
Master Contents Master Index Help On Help
12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
Page 270 CFX-5 Tutorials
Master Contents Master Index Help On Help
Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 271
Master Contents Master Index Help On Help
12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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Flow in an Axial RotorStatormdashViewing the Results
Page 272 CFX-5 Tutorials
Master Contents Master Index Help On Help
6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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CFX-5 Tutorials Page 273
Master Contents Master Index Help On Help
One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 275
Master Contents Master Index Help On Help
2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 277
Master Contents Master Index Help On Help
12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 278 CFX-5 Tutorials
Master Contents Master Index Help On Help
12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 279
Master Contents Master Index Help On Help
5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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CFX-5 Tutorials Page 281
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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CFX-5 Tutorials Page 285
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
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Flow in an Axial RotorStatormdashIntroduction
Page 258 CFX-5 Tutorials
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12A Introduction
12A1 Features explored in this tutorial
Introduction This tutorial addresses the following features of CFX-5
Component Feature Details
CFX-Pre User Mode Turbo Wizard
Simulation Type Steady State
Transient
Fluid Type Ideal Gas
Domain Type Multiple Domain
Rotating Frame of
Reference
Turbulence Model k-Epsilon
Heat Transfer Total EnergyBoundary Conditions Inlet (Subsonic)
Outlet (Subsonic)
Wall No-Slip
Wall Adiabatic
Domain Interfaces Frozen Rotor
Periodic
Transient Rotor Stator
Timestep Physical Timescale
Transient Example
Transient Results File
CFX-Solver Manager Restart
Parallel Processing
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You learn about
bull using the Turbo Wizard in CFX-Pre to quickly specify a turbomachineryapplication
bull multiple Frames of Reference and Generalised Grid Interface
bull using a Frozen Rotor interface between the rotor and stator domains
bull modifying an existing simulation
bull setting up a transient calculation
bull using a Transient Rotor-Stator interface condition to replace a Frozen
Rotor interface
bull creating a transient animation showing domain movement in CFX-Post
12A2 Before beginning this tutorial
Introduction It is necessary that you have a working directory and that
sample files have been copied to that directory This procedure is detailed
in Introduction to the CFX-5 Tutorials on page 1
Unless you review the introductory materials and perform required steps
including setting up a working directory and copying related sample files
the rest of this tutorial may not work correctly It is recommended that you
perform the tasks in Tutorial 1 Tutorial 2 and Tutorial 3 before working with
other tutorials as these three tutorials detail specific procedures that are
simplified in subsequent tutorials
CFX-Post Plots Animation
Isosurface
Surface Group
Turbo Post
Other Changing the Colour
Range
Chart Creation
Instancing Transformation
MPEG Generation
Quantitative Calculation
Timestep Selection
Transient Animation
Component Feature Details
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Page 260 CFX-5 Tutorials
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12A3 Overview of the problem to solve
The following tutorial demonstrates the versatility of GGI and MFR in
CFX-Pre by combining two dissimilar meshes The first mesh to be imported
(the rotor) was created in CFX-TurboGrid This is combined with a second
Definition File mesh (the stator)
The geometry to be modelled consists of a single stator blade passage andtwo rotor blade passages The rotor rotates about the Z axis while the stator
is stationary Periodic boundaries are used to allow only a small section of
the full geometry to be modelled
Figure 1
At the change in reference frame between the rotor and stator twodifferent interface models are considered First a solution is obtained using
a frozen rotor model After viewing the results from this simulation the
CFX-Pre simulation is modified to use a transient rotor-stator interface
model The frozen rotor solution is used as an initial guess for the transient
rotor-stator simulation
Hub
Rotor Blade
Outflow
Shroud
Stator Blade
Inflow
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The full geometry contains 60 stator blades and 113 rotor blades To help
you visualise how the modelled geometry fits into the full geometryFigure
1 on page 260 the image shows approximately half of the full geometry
The Inflow and Outflow labels show the location of the modelled section in
Figure 2 on page 261
Figure 2 The modelled geometry contains two rotor blades and one stator blade
This is an approximation to the full geometry since the ratio of rotor blades
to stator blades is close to but not exactly 21 In the stator blade passage a
6deg section is being modelled (360deg 60 blades) while in the rotor blade
passage a 6372deg section is being modelled (2360deg 113 blades) This
produces a pitch ratio at the interface between the stator and rotor of 0942
where the pitch ratio is the area of side 1 divided by the area of side 2 As the
flow crosses the interface it is scaled to allow this type of geometry to be
modelled This results in an approximation of the inflow to the rotorpassage Furthermore the flow across the interface will not appear
continuous due to the scaling applied
The periodic boundary conditions will introduce an additional
approximation since they cannot be periodic when a pitch change occurs
Inflow
Outflow
Axis of Rotation
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You should always try to obtain a pitch ratio as close to 1 as possible in your
model to minimise approximations but this must be weighed against
computational resources A full machine analysis can be performed
(modelling all rotor and stator blades) which will always eliminate any pitch
change but will require significant computational time For this rotorstator
geometry a 14 machine section (28 rotor blades 15 stator blades) would
produce a pitch change of 1009 but this would require a model about 15times larger than in this tutorial example
If you have already completed the frozen rotor part of this tutorial you can
continue from Setting up the Transient Rotor-Stator Calculation (p 276)
Note that a converged results file from the frozen rotor section is required
as an initial guess You can use your own solution or use the results file
provided in the examples directory Further details are given inObtaining a
Solution to the Transient Rotor-Stator Model (p 280) You must make sure
that the boundary names used in the initial results file exactly match those
used in the transient rotor-stator case
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CFX-5 Tutorials Page 263
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12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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CFX-5 Tutorials Page 265
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13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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CFX-5 Tutorials Page 267
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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Page 268 CFX-5 Tutorials
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
CFX-5 Tutorials Page 269
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Page 270 CFX-5 Tutorials
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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CFX-5 Tutorials Page 275
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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CFX-5 Tutorials Page 277
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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CFX-5 Tutorials Page 279
Master Contents Master Index Help On Help
5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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CFX-5 Tutorials Page 283
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashIntroduction
CFX-5 Tutorials Page 259
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You learn about
bull using the Turbo Wizard in CFX-Pre to quickly specify a turbomachineryapplication
bull multiple Frames of Reference and Generalised Grid Interface
bull using a Frozen Rotor interface between the rotor and stator domains
bull modifying an existing simulation
bull setting up a transient calculation
bull using a Transient Rotor-Stator interface condition to replace a Frozen
Rotor interface
bull creating a transient animation showing domain movement in CFX-Post
12A2 Before beginning this tutorial
Introduction It is necessary that you have a working directory and that
sample files have been copied to that directory This procedure is detailed
in Introduction to the CFX-5 Tutorials on page 1
Unless you review the introductory materials and perform required steps
including setting up a working directory and copying related sample files
the rest of this tutorial may not work correctly It is recommended that you
perform the tasks in Tutorial 1 Tutorial 2 and Tutorial 3 before working with
other tutorials as these three tutorials detail specific procedures that are
simplified in subsequent tutorials
CFX-Post Plots Animation
Isosurface
Surface Group
Turbo Post
Other Changing the Colour
Range
Chart Creation
Instancing Transformation
MPEG Generation
Quantitative Calculation
Timestep Selection
Transient Animation
Component Feature Details
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12A3 Overview of the problem to solve
The following tutorial demonstrates the versatility of GGI and MFR in
CFX-Pre by combining two dissimilar meshes The first mesh to be imported
(the rotor) was created in CFX-TurboGrid This is combined with a second
Definition File mesh (the stator)
The geometry to be modelled consists of a single stator blade passage andtwo rotor blade passages The rotor rotates about the Z axis while the stator
is stationary Periodic boundaries are used to allow only a small section of
the full geometry to be modelled
Figure 1
At the change in reference frame between the rotor and stator twodifferent interface models are considered First a solution is obtained using
a frozen rotor model After viewing the results from this simulation the
CFX-Pre simulation is modified to use a transient rotor-stator interface
model The frozen rotor solution is used as an initial guess for the transient
rotor-stator simulation
Hub
Rotor Blade
Outflow
Shroud
Stator Blade
Inflow
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The full geometry contains 60 stator blades and 113 rotor blades To help
you visualise how the modelled geometry fits into the full geometryFigure
1 on page 260 the image shows approximately half of the full geometry
The Inflow and Outflow labels show the location of the modelled section in
Figure 2 on page 261
Figure 2 The modelled geometry contains two rotor blades and one stator blade
This is an approximation to the full geometry since the ratio of rotor blades
to stator blades is close to but not exactly 21 In the stator blade passage a
6deg section is being modelled (360deg 60 blades) while in the rotor blade
passage a 6372deg section is being modelled (2360deg 113 blades) This
produces a pitch ratio at the interface between the stator and rotor of 0942
where the pitch ratio is the area of side 1 divided by the area of side 2 As the
flow crosses the interface it is scaled to allow this type of geometry to be
modelled This results in an approximation of the inflow to the rotorpassage Furthermore the flow across the interface will not appear
continuous due to the scaling applied
The periodic boundary conditions will introduce an additional
approximation since they cannot be periodic when a pitch change occurs
Inflow
Outflow
Axis of Rotation
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You should always try to obtain a pitch ratio as close to 1 as possible in your
model to minimise approximations but this must be weighed against
computational resources A full machine analysis can be performed
(modelling all rotor and stator blades) which will always eliminate any pitch
change but will require significant computational time For this rotorstator
geometry a 14 machine section (28 rotor blades 15 stator blades) would
produce a pitch change of 1009 but this would require a model about 15times larger than in this tutorial example
If you have already completed the frozen rotor part of this tutorial you can
continue from Setting up the Transient Rotor-Stator Calculation (p 276)
Note that a converged results file from the frozen rotor section is required
as an initial guess You can use your own solution or use the results file
provided in the examples directory Further details are given inObtaining a
Solution to the Transient Rotor-Stator Model (p 280) You must make sure
that the boundary names used in the initial results file exactly match those
used in the transient rotor-stator case
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CFX-5 Tutorials Page 263
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12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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Page 264 CFX-5 Tutorials
Master Contents Master Index Help On Help
different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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CFX-5 Tutorials Page 265
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13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Page 266 CFX-5 Tutorials
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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12A3 Overview of the problem to solve
The following tutorial demonstrates the versatility of GGI and MFR in
CFX-Pre by combining two dissimilar meshes The first mesh to be imported
(the rotor) was created in CFX-TurboGrid This is combined with a second
Definition File mesh (the stator)
The geometry to be modelled consists of a single stator blade passage andtwo rotor blade passages The rotor rotates about the Z axis while the stator
is stationary Periodic boundaries are used to allow only a small section of
the full geometry to be modelled
Figure 1
At the change in reference frame between the rotor and stator twodifferent interface models are considered First a solution is obtained using
a frozen rotor model After viewing the results from this simulation the
CFX-Pre simulation is modified to use a transient rotor-stator interface
model The frozen rotor solution is used as an initial guess for the transient
rotor-stator simulation
Hub
Rotor Blade
Outflow
Shroud
Stator Blade
Inflow
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The full geometry contains 60 stator blades and 113 rotor blades To help
you visualise how the modelled geometry fits into the full geometryFigure
1 on page 260 the image shows approximately half of the full geometry
The Inflow and Outflow labels show the location of the modelled section in
Figure 2 on page 261
Figure 2 The modelled geometry contains two rotor blades and one stator blade
This is an approximation to the full geometry since the ratio of rotor blades
to stator blades is close to but not exactly 21 In the stator blade passage a
6deg section is being modelled (360deg 60 blades) while in the rotor blade
passage a 6372deg section is being modelled (2360deg 113 blades) This
produces a pitch ratio at the interface between the stator and rotor of 0942
where the pitch ratio is the area of side 1 divided by the area of side 2 As the
flow crosses the interface it is scaled to allow this type of geometry to be
modelled This results in an approximation of the inflow to the rotorpassage Furthermore the flow across the interface will not appear
continuous due to the scaling applied
The periodic boundary conditions will introduce an additional
approximation since they cannot be periodic when a pitch change occurs
Inflow
Outflow
Axis of Rotation
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You should always try to obtain a pitch ratio as close to 1 as possible in your
model to minimise approximations but this must be weighed against
computational resources A full machine analysis can be performed
(modelling all rotor and stator blades) which will always eliminate any pitch
change but will require significant computational time For this rotorstator
geometry a 14 machine section (28 rotor blades 15 stator blades) would
produce a pitch change of 1009 but this would require a model about 15times larger than in this tutorial example
If you have already completed the frozen rotor part of this tutorial you can
continue from Setting up the Transient Rotor-Stator Calculation (p 276)
Note that a converged results file from the frozen rotor section is required
as an initial guess You can use your own solution or use the results file
provided in the examples directory Further details are given inObtaining a
Solution to the Transient Rotor-Stator Model (p 280) You must make sure
that the boundary names used in the initial results file exactly match those
used in the transient rotor-stator case
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CFX-5 Tutorials Page 263
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12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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Page 264 CFX-5 Tutorials
Master Contents Master Index Help On Help
different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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CFX-5 Tutorials Page 265
Master Contents Master Index Help On Help
13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Page 266 CFX-5 Tutorials
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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CFX-5 Tutorials Page 267
Master Contents Master Index Help On Help
2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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Page 268 CFX-5 Tutorials
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
CFX-5 Tutorials Page 269
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Page 270 CFX-5 Tutorials
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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CFX-5 Tutorials Page 277
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Master Contents Master Index Help On Help
12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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CFX-5 Tutorials Page 283
Master Contents Master Index Help On Help
5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
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Flow in an Axial RotorStatormdashIntroduction
CFX-5 Tutorials Page 261
Master Contents Master Index Help On Help
The full geometry contains 60 stator blades and 113 rotor blades To help
you visualise how the modelled geometry fits into the full geometryFigure
1 on page 260 the image shows approximately half of the full geometry
The Inflow and Outflow labels show the location of the modelled section in
Figure 2 on page 261
Figure 2 The modelled geometry contains two rotor blades and one stator blade
This is an approximation to the full geometry since the ratio of rotor blades
to stator blades is close to but not exactly 21 In the stator blade passage a
6deg section is being modelled (360deg 60 blades) while in the rotor blade
passage a 6372deg section is being modelled (2360deg 113 blades) This
produces a pitch ratio at the interface between the stator and rotor of 0942
where the pitch ratio is the area of side 1 divided by the area of side 2 As the
flow crosses the interface it is scaled to allow this type of geometry to be
modelled This results in an approximation of the inflow to the rotorpassage Furthermore the flow across the interface will not appear
continuous due to the scaling applied
The periodic boundary conditions will introduce an additional
approximation since they cannot be periodic when a pitch change occurs
Inflow
Outflow
Axis of Rotation
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Page 262 CFX-5 Tutorials
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You should always try to obtain a pitch ratio as close to 1 as possible in your
model to minimise approximations but this must be weighed against
computational resources A full machine analysis can be performed
(modelling all rotor and stator blades) which will always eliminate any pitch
change but will require significant computational time For this rotorstator
geometry a 14 machine section (28 rotor blades 15 stator blades) would
produce a pitch change of 1009 but this would require a model about 15times larger than in this tutorial example
If you have already completed the frozen rotor part of this tutorial you can
continue from Setting up the Transient Rotor-Stator Calculation (p 276)
Note that a converged results file from the frozen rotor section is required
as an initial guess You can use your own solution or use the results file
provided in the examples directory Further details are given inObtaining a
Solution to the Transient Rotor-Stator Model (p 280) You must make sure
that the boundary names used in the initial results file exactly match those
used in the transient rotor-stator case
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CFX-5 Tutorials Page 263
Master Contents Master Index Help On Help
12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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Page 264 CFX-5 Tutorials
Master Contents Master Index Help On Help
different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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CFX-5 Tutorials Page 265
Master Contents Master Index Help On Help
13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Page 266 CFX-5 Tutorials
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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CFX-5 Tutorials Page 267
Master Contents Master Index Help On Help
2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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Page 268 CFX-5 Tutorials
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
CFX-5 Tutorials Page 269
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Page 270 CFX-5 Tutorials
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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Page 272 CFX-5 Tutorials
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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CFX-5 Tutorials Page 275
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 277
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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CFX-5 Tutorials Page 279
Master Contents Master Index Help On Help
5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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CFX-5 Tutorials Page 283
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashIntroduction
Page 262 CFX-5 Tutorials
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You should always try to obtain a pitch ratio as close to 1 as possible in your
model to minimise approximations but this must be weighed against
computational resources A full machine analysis can be performed
(modelling all rotor and stator blades) which will always eliminate any pitch
change but will require significant computational time For this rotorstator
geometry a 14 machine section (28 rotor blades 15 stator blades) would
produce a pitch change of 1009 but this would require a model about 15times larger than in this tutorial example
If you have already completed the frozen rotor part of this tutorial you can
continue from Setting up the Transient Rotor-Stator Calculation (p 276)
Note that a converged results file from the frozen rotor section is required
as an initial guess You can use your own solution or use the results file
provided in the examples directory Further details are given inObtaining a
Solution to the Transient Rotor-Stator Model (p 280) You must make sure
that the boundary names used in the initial results file exactly match those
used in the transient rotor-stator case
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CFX-5 Tutorials Page 263
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12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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CFX-5 Tutorials Page 267
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Page 270 CFX-5 Tutorials
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 277
Master Contents Master Index Help On Help
12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
Master Contents Master Index Help On Help
12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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CFX-5 Tutorials Page 279
Master Contents Master Index Help On Help
5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
Page 280 CFX-5 Tutorials
Master Contents Master Index Help On Help
12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 281
Master Contents Master Index Help On Help
12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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Page 282 CFX-5 Tutorials
Master Contents Master Index Help On Help
6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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CFX-5 Tutorials Page 283
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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Page 284 CFX-5 Tutorials
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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CFX-5 Tutorials Page 285
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
CFX-5 Tutorials Page 263
Master Contents Master Index Help On Help
12B Defining the Frozen-Rotor Simulation in
CFX-Pre
This section describes the step-by-step definition of the flow physics in
CFX-Pre If you wish you can use the session file AxialInipre to
complete this section for you and continue fromObtaining a Solution to theFrozen Rotor Simulation (p 269) See one of the first four tutorials for
instructions on how to do this
12B1 Creating a New Simulation
This tutorial will use the Turbo Wizard in CFX-Pre This pre-processing mode
is designed to simplify the setup of turbomachinery simulations
1 Start CFX-Pre
2 Select File gt New Simulation
New Simulation File appears
3 Click the Turbo icon in the area at right to highlight it
4 Browse the folders as necessary then enter the file nameAxialIni
5 Click Save
The Turbo Wizard will appear in the User Mode workspace which is
part of the general CFX-Pre workspace
12B2 Component Definition
The first step is to define the rotational axis machine type and simulation
state The names of the turbo regions for the domains will also be set
When the Turbo Wizard appears
1 Set Rotational Axis to Z
2 Leave Simulation Type set to Steady State
3 Expand the Turbo Regions frame This shows the regions that CFX-Pre attempts to automatically assign to
appropriate boundary conditions To do this it needs to know the region
names to expect in the mesh files The upper case Turbo Regions that are
selected (eg HUB) correspond to the region names in the CFX-TASCflow
ldquogrdrdquo file CFX-TASCflow turbomachinery meshes use these names
consistently The lower case Turbo Regions correspond to the region names
in the CFX-5 Definition file CFX-5 turbomachinery meshes may have
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Page 264 CFX-5 Tutorials
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different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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CFX-5 Tutorials Page 265
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13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Page 266 CFX-5 Tutorials
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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CFX-5 Tutorials Page 267
Master Contents Master Index Help On Help
2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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Page 268 CFX-5 Tutorials
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
CFX-5 Tutorials Page 269
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
Page 270 CFX-5 Tutorials
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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CFX-5 Tutorials Page 275
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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CFX-5 Tutorials Page 277
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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CFX-5 Tutorials Page 279
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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different region names than these In this case just leave the Turbo Regions
frame with its default settings you will be able to assign regions to
boundary conditions later
4 Click Next gt
12B3 Importing the Meshes
Tip While we provide a mesh to use with this tutorial you may want to
develop your own in the future Instructions on how to create this meshin CFX-Mesh are available from the CFX Community Site Please seeMesh Generation on page 3 for details
The first step is to import the two different mesh files One mesh file
contains the rotor mesh in a CFX-TASCflow ldquogrdrdquo file while the other mesh
file contains the stator in a CFX-5 Definition file
1 Copy the filesrotorgrd andstatordef located in the examples
directory (ltCFXROOTgtexamples) to your working directory
2 On the Stage Definition form click New
3 Set Name to S2 then click OK
4 Set Component Type to Stationary
5 Click to the right of Select Mesh
An Import Mesh form will appear beneath the Turbo Wizard
6 On the Import Mesh forma Set Mesh Format to CFX-5 DefRes file
b Set File to statordef
c Click OK to import the mesh
7 In the Select Mesh drop-down list ensure that Default is selected
8 On the Stage Definition form click New
9 Set Name to R1 then click OK
10 Set Component Type to Rotating11 Set Speed to 5236 [radian s^-1]
12 Click to the right of Select Mesh
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13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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CFX-5 Tutorials Page 267
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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Page 268 CFX-5 Tutorials
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Frozen Rotor Simulation
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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13 On the Import Mesh form
a Set Mesh Format to CFX-TASCflow v2
b Set File to rotorgrd
c Click OK to import the mesh
You will receive a warning message when importing this mesh The
message will tell you the information that has been ignored duringimport See CFX-TASCflow v2 on page 91 in the document CFX-Pre
for further details on this and importing CFX-TASCflow meshes
14 Click OK on the warning message to continue
15 Set Select Mesh to Assembly 3D
16 Click Next gt to continue
12B4 Creating the Interfaces
Here you will set up appropriate periodic interfaces on the rotor and stator
These are required since you are only modelling a small section of the true
geometry An interface is also required to connect the two meshes together
across the frame change See Domain Interfaces on page 299 in the
document CFX-Pre for more details
CFX-Pre will try to create appropriate interfaces using the Turbo Region
names shown earlier In this case CFX-Pre has displayed the definition of
three interfaces The following steps will verify that the interface definitions
are correct
Rotor PeriodicInterface
The first interface is named R1 to R1 Periodic
1 Click the interface to display the Interface definition
2 As expected a periodic interface has been created for the rotor domain
and the regions selected for the interface are correct
3 These are the correct settings for the periodic interface so no further
action is required
Stator PeriodicInterface
1 Click the S2 to S2 Periodic interface
2 The Interface Definition shows a periodic interface for the stator
domain showing the correct regions
3 No further action is required for this interface
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
Page 266 CFX-5 Tutorials
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Frozen RotorDomainInterface
1 Click the R1 to S2 Stage interface
2 The correct regions INFLOW and out have been selected for this
interface
3 The intention is to use a Frozen Rotor interface in this tutorial so change
Type to Frozen Rotor
Note If inappropriate interface conditions were created automatically youcan highlight and delete them using the delete icon
4 Click Next gt
12B5 General Physics
The General Physics form will now be displayed
1 In the Fluid drop-down list select Air Ideal Gas
2 Under Model Data
a Set Reference Pressure to 025 [bar]
Note the change in units from Pa to bar
b Leave Heat Transfer set to Total Energy
c Leave Turbulence set to k-Epsilon (scalable wall function)
3 Under Solver Parameters
a Leave Advection Scheme set to High Resolution
b Set Convergence Control to Physical Timescale and PhysicalTimescale to 0002 [s]
This timescale is approximately equal to 1 ω which is often
appropriate for rotating machinery applications
4 Click Next gt to continue
12B6 Boundary Definition
CFX-Pre will now try to create appropriate boundary conditions using the
Turbo Region names shown earlier The Boundary Definition form willappear showing a list of boundary conditions These were automatically
created and can be viewed edited and deleted in the same way as the
interface connections that were set up earlier
Setting theStator InletBoundaryCondition
1 Click Inlet
Location and Boundary Type are both correct so there is no need to
change these settings
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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CFX-5 Tutorials Page 267
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2 Under Flow Specification set Option to Stationary Frame Total
Pressure and Relative Pressure to 0 [Pa]
3 Leave Flow Direction set to Normal to Boundary
4 Set Total Temperature to 340 [K]
To set therotor outletboundarycondition
1 Click OutletLocation and Boundary Type are both correct so there is no need to
change these settings
2 Under Flow Specification set Option to Mass Flow Rate and Mass
Flow Rate to 006 [kg s^-1]
Checking theRotor BladeBoundaryCondition
Click Blade a wall boundary specified on the BLADE region Note that all of
the details are correct for this boundary condition
Wall boundary conditions are created relative to the local domain reference
frame by default so this boundary is stationary relative to the rotatingdomain (ie rotating relative to the stationary domain)
Checking theRotor HubBoundaryCondition
Click Hubawallboundaryonthe HUB region Note that all of the details are
correct for this boundary condition
Checking theRotor ShroudBoundary
Condition
Click Shroud a wall boundary on the SHROUD region Note that all of the
details are correct for this boundary condition
Checking theRemainingBoundaries
1 Click on the boundaries Blade 2 Hub 2 and Shroud 2 Wall boundaries
will be shown on the regions blade hub and shroud respectively and
need no editing
Note If inappropriate boundary conditions are created by CFX-Pre or aremissing you can delete and add them as appropriate
2 Click Next gt to continue
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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CFX-5 Tutorials Page 279
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashDefining the Frozen-Rotor Simulation in CFX-Pre
Page 268 CFX-5 Tutorials
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12B7 File Definition Options
The last form offers the following three options
bull Enter General Mode
bull Start Solver Write the Solver (def) File enter General Mode and start
the CFX-Solver
bull Start Solver and Quit Write the Solver (def) File start the CFX-Solverand quit CFX-Pre
1 Select Start Solver and Quit then click Finish
2 Answer Yes when asked if you want to save the CFX file
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Page 270 CFX-5 Tutorials
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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12C Obtaining a Solution to the Frozen Rotor
Simulation
Compared to previous tutorials the mesh for this tutorial contains many
more nodes (although it is still too coarse to perform a high quality CFD
simulation) This results in a corresponding increase in solution time for theproblem We recommend solving this problem in parallel It is
recommended that your machine has a minimum of 256MB of memory to
run this tutorial
Note If you do not have a license to run CFX-5 in parallel you can run inserial by clicking the Start Run button when CFX-Solver Manager has
opened up Solution time in serial is approximately 45 minutes on a 1GHzprocessor
Instructions are provided below to run this tutorial in parallel More detailedinformation about setting up CFX-5 to run in parallel is provided in Flow
Arounda Blunt Body on page 123 and in Setting Up and Running a Parallel
Run on page 45 in the document CFX- Solver Manager
You can solve this example using either Local Parallel or Distributed Parallel
as guidance is provided for both
Solving UsingLocal Parallel
To run in Local Parallel the machine you are on must have more than one
processor
1 On the Define Run form set Run Mode to PVM Local Parallel (this isthe recommended method for most applications see Run Mode on
page 12 in the document CFX- Solver Manager for details on the other
options)
2 By default 2 partitions are assigned Click Add Partition to add
more partitions
3 Click Start Run
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
4 Click Post-Process Results
5 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
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Solving UsingDistributedParallel
1 On the Define Run form set Run Mode to PVM Distributed Parallel
1 partition should already be assigned to the host that you are logged
into
2 Click Select Host to specify a new parallel host
3 In Select Parallel Hosts select another Host Name (this should be a
machine that you can log into using the same user name)
4 Click Add then Close
The names of the two selected machines should be listed in the Host
Name column of the Define Run form
5 Click Start Run
Notice that the pitch ratio is written near the start of the OUT file for a
parallel run
+--------------------------------------------------------------------+
| Total Number of Nodes Elements and Faces |+--------------------------------------------------------------------+Domain Interface Name Auto Interface 3
Non-overlap area fraction on side 1 = 00Non-overlap area fraction on side 2 = 01Area based pitch ratio (6372 leg 6000 leg) = 1062
During convergence data is written to an out file for each equation in
each fluid domain separately
When the Solver has finished
6 Click Post-Process Results
7 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
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12D Viewing the Results
The Turbo-Post feature will be demonstrated in the following sections This
feature is designed to greatly reduce the effort taken to post-process
turbomachinery simulations A number of turbo-specific features are also
available see CFX-Post Turbo Menu on page 171 in the document
CFX-Post for more details
Initialising Turbo-Post
To initialise Turbo-Post the properties of each componentmustbe entered
This includes entering information about the inlet outlet hub shroud
blade and periodic regions
1 Select Turbo gt Turbo Mode from the main menu
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent is set to 2 These settings are correct for
this component4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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CFX-5 Tutorials Page 277
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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CFX-5 Tutorials Page 279
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
Master Contents Master Index Help On Help
12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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Master Contents Master Index Help On Help
6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Page 272 CFX-5 Tutorials
Master Contents Master Index Help On Help
6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
Colouring aSurface of Constant Span
1 Open the Turbo Plotter by selecting Turbo gt Turbo Plotter from the
main menu
2 Click the Run Initial Setup button (located at the bottom right of the
Turbo Plotter form)
bull Three objects are created in separate viewports when the Initial
Setup option is chosen Turbo 3D view 2D Blade-to-Blade view and
2D Meridional view
bull In this case the meridional turbo surface will obscure part of the
plots you will be creating in the next steps
3 In the Object Selector turn off the visibility for theTurbo Plotter Merid
Surface
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Page 276 CFX-5 Tutorials
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
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One of the default objects created when you ran the initial setup is a
blade-to-blade turbo surface drawn at a spanwise location of 05 (halfway
between the hub and shroud) For an explanation of turbo locations please
see Turbo Measurements on page 187 in the document CFX-Post Here
you will colour the surface with pressure
1 In the Object Selector right-click the Turbo Plotter B2B Surface and
select Edit
2 Click the Colour tab and set
a Mode to Variable
b Variable to Pressure
c Range to Global
3 Click Apply
Viewing 3
domainpassages
Next you will create an instancing transformation to plot three blade
passages for the stator and six blade passages for the rotor
The instancing properties of each domain have already been entered
during Initialisation In the next steps you will create a surface group plot
(see Surface Group on page 94 in the document CFX-Post) to colour the
blade and hub surfaces with the same variable The number of instances of
for each domain will then be changed
1 Use the Object Selector to make all objects invisible
2 Select Create gt Object gt Surface Group from the main menu
3 Accept the default name and click OK
4 Set Locations to Hub Hub 2 Blade and Blade 2(use the icon to
open the Locations Selector)
5 On the Colour panel set Mode to Variable and Variable to Pressure
6 Click Apply
7 In the Turbo Plotter make sure Plot is set to Turbo 3D View
8 Under Instancing set of Copies for the R1 domain to 3
9 Click Apply
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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Master Contents Master Index Help On Help
5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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10 Carry out the same step for the S2 domain
Creating aBlade LoadingChart
In this section you will create a plot of pressure around the stator blade at a
given spanwise location For more details on this functionality please see
Turbo Plotter Turbo Chart on page 192 in the document CFX-Post
1 In the Turbo Plotter set
a Plot to Turbo Chart
b Type to Blade Loading
c Domain to S2
d Span to 05e X Variable to Z
f Y Variable to Pressure
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2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
Page 280 CFX-5 Tutorials
Master Contents Master Index Help On Help
12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 281
Master Contents Master Index Help On Help
12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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Master Contents Master Index Help On Help
6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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CFX-5 Tutorials Page 283
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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Page 284 CFX-5 Tutorials
Master Contents Master Index Help On Help
5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Master Contents Master Index Help On Help
2 Click Apply
A turbo line is automatically created in the viewer to show where
pressure values have been sampled
The profile of the pressure curve is typical in turbomachinery applications
This completes the frozen-rotor part of the tutorial The next section
describes how to use the solution to set up a transient rotor-stator
calculation
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 276 CFX-5 Tutorials
Master Contents Master Index Help On Help
12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 277
Master Contents Master Index Help On Help
12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 278 CFX-5 Tutorials
Master Contents Master Index Help On Help
12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
Page 280 CFX-5 Tutorials
Master Contents Master Index Help On Help
12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashViewing the Results
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Master Contents Master Index Help On Help
12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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Master Contents Master Index Help On Help
6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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Flow in an Axial RotorStatormdashViewing the Results
Page 284 CFX-5 Tutorials
Master Contents Master Index Help On Help
5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 276 CFX-5 Tutorials
Master Contents Master Index Help On Help
12E Setting up the Transient Rotor-Stator
Calculation
This section describes the step-by-step definition of the flow physics in
CFX-Pre The existing frozen-rotor simulation is modified to define the
transient rotor-stator simulation If you wish you can use the session fileAxialpre to complete this section for you and continue fromObtaining
a Solution to the Transient Rotor-Stator Model (p 280) See one of the first
four tutorials for instructions on how to do this
Note The session file creates a newsimulation namedAxialcfx and willnot modify the existing database It also copies the required initial values
files from the examples directory to the current working directory
12E1 Opening the Existing Simulation
This step involves opening the original simulation and saving it to a
different location
1 Start CFX-Pre and select File gt Open Simulation
2 Select the original simulation fileAxialIni_001res
bull You will need to change the import filter to showdef and
res files
bull If you have not completed the first part of the tutorial this file can
be copied from the examples directory
3 Select File gt Save Simulation As
4 Enter Axial and click OK
The simulation will open in General Mode The Turbo-Pre Wizard can be
used to quickly create turbomachinery cases but General Mode is always
used when re-opening a simulation
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 277
Master Contents Master Index Help On Help
12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 278 CFX-5 Tutorials
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 279
Master Contents Master Index Help On Help
5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 277
Master Contents Master Index Help On Help
12E2 Modifying the Simulation Type
You need to modify the domain to define a transient simulation You are
going to run for a time interval such that the rotor blades pass through 1
pitch (6372o) using 10 timesteps This is generally too few timesteps to
obtain high quality results but is sufficient for tutorial purposes The
timestep size is calculated as followsRotational Speed = 5236 radsRotor Pitch Modelled = 2(2π113) = 01112 radTime to pass through 1 pitch = 011125236 = 2124e-4 s
Since 10 timesteps are going to be used over this interval then each
timestep should be 2124e-5s
1 Select Create gt Flow Objects gt Simulation Type from the main menu
2 On the Basic Settings panel set Option to Transient
3 Under Time Duration
a Set Option to Total Time and Total Time to 2124e-4 [s]
This gives 10 timesteps of 2124e-5 s
b Set Timesteps to 2124e-5 and leave the units set to [s]
This timestep will be used until the total time is reached
4 Under Initial Time set Option to Automatic with Value and Time to
0 [s]
5 Click OK
Note A transient rotor-stator calculation often runs through more than onepitch In these cases it may be useful to look at variable data averaged overthe time interval required to complete 1 pitch You can then compare datafor each pitch rotation to see if a ldquosteady staterdquo has been achieved or if theflow is still developing See Using Statistics with Transient Rotor-StatorCases on page 335 in the document CFX-Pre for details on how to get
time averaged variable data
12E3 Modifying the Domain Interface
1 In the Physics Workspace double click R1 to S2 Stage
2 Under FrameChange set Option to Transient RotorStatorthenclick
OK
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12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
Page 280 CFX-5 Tutorials
Master Contents Master Index Help On Help
12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
Page 278 CFX-5 Tutorials
Master Contents Master Index Help On Help
12E4 Setting Initial Values
When defining a simulation using the Turbo Wizard initial values are not set
since the default is Automatic for all variables When the Simulation Type
waschanged to Transient CFX-Pre signalled a Physics Validation error since
initial values are required for all transient runs The initial values must either
be specified or provided by selecting an Initial Values File in the CFX-SolverManager when defining the run In this tutorial the solution from the Frozen
Rotor simulation will be used as the Initial Values File
Ignoring the Physics Validation warning andlater specifying an initial values
file in the CFX-Solver would still allow the problem to run (because the
CFX-Solverwould still attempt to run the simulation with Automaticvalues)
but in this tutorial the values will be explicitly set to Automatic to remove
the Physics Validation warning
1 Click Global Initialisation
2 Change all of the options that are currently set to Automatic with
Value to Automatic
3 Turn on Turbulence Eddy Dissipation and set Option to Automatic
4 Click OK
12E5 Modifying the Solver Control
1 Click Solver Control
2 Set Max Iter Per Timestep to 3
We do not generally recommend using a large number of iterations per
timestep see Transient Timestep Control on page 352 in the
document CFX-5 Solver Modelling for details
3 Click OK to set the solver parameters
12E6 Creating Transient Results Files
1 Click Output Control
2 Click the Transient Results tab
3 Click Add new item and then click OK to accept the default name
for the object
4 Leave Option set to Minimal
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5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
Page 280 CFX-5 Tutorials
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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Flow in an Axial RotorStatormdashViewing the Results
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
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Flow in an Axial RotorStatormdashViewing the Results
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Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
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Flow in an Axial RotorStatormdashSetting up the Transient Rotor-Stator Calculation
CFX-5 Tutorials Page 279
Master Contents Master Index Help On Help
5 Set Output Variable List to Pressure Velocity and Velocity in Stn
Frame (use the ltCtrlgt key to select more than one variable)
Note Velocity is always defined in the local reference frame so it will givethe rotating frame velocity in the rotor component
6 Turn on Time Interval and set Time Interval to 2124e-5 [s]
7 Click OK
12E7 Writing the Solver (def) File
1 Click Create Definition File
2 Set File name to Axialdef
3 Leave Operation set to Start Solver Manager with def file
4 Turn on Report Summary of Interface Connections
5 Click OK
The Information window shows that the fluid-fluid interface is GGI and
the two periodic interfaces are one-to-one
6 Click OK in the information window
7 Select File gt Quit
8 Click Yes when asked if you want to save the CFX file
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
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12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
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Flow in an Axial RotorStatormdashObtaining a Solution to the Transient Rotor-Stator Model
Page 280 CFX-5 Tutorials
Master Contents Master Index Help On Help
12F Obtaining a Solution to the Transient
Rotor-Stator Model
When the CFX-Solver Manager has started you will need to specify an Initial
Values File before starting the CFX-Solver Set Initial Values File to
AxialIni_001res (the Frozen Rotor solution)
12F1 Serial Solution
If you do not have a license or do not want to run CFX-5 in parallel you can
runin serial by clicking the StartRun button Solution time in serial is similar
to the first part of this tutorial
12F2 Parallel Solution
You can solve this example using either Local Parallel or Distributed Parallel
in the same way as in the first part of this tutorial See Obtaining a Solution
to the Frozen Rotor Simulation (p 269) if you need further guidance
12F3 Monitoring the Run
During the solution look for the additional information that is provided for
transient rotor-stator runs Each time the rotor is rotated to its next position
the number of degrees of rotation and the fraction of a pitch moved is
given You should see that after 10 timesteps the rotor has been movedthrough 1 pitch
You will notice a jump in the residuals (to the order of 10E-2) for every
timestep This is to be expected for a transient simulation under these
conditions which in the interest of time has a large timestep You will also
notice that the problem does not converge to the convergence criteria in a
single timestep and for accurate results reaching the convergence criteria
is very important Convergence is achieved by adjusting the length of the
timestep to an appropriate valueTransient Timestep Control on page 352
in the document CFX-5 Solver Modelling
When the Solver has finished
1 Click Post-Process Results
2 When Start CFX-Post appears turn on Shut down Solver Manager
then click OK
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12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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Flow in an Axial RotorStatormdashViewing the Results
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 281
Master Contents Master Index Help On Help
12G Viewing the Results
To examine the transient interaction between the rotor and stator you are
going to create a blade-to-blade animation of pressure A turbo surface will
be used as the basis for this plot
Initialising Turbo-Post
To initialise Turbo-post the properties of each domain must be entered This includes entering information about the inlet outlet hub shroud
blade and periodic regions The instancing properties are set on the
Instancing tab menu
1 Select Turbo gt Turbo Mode from the main menu bar
The Turbo tab is automatically selected and shows the two components in
domains R1 and S2 In the next step both of these components will be
initialised
1 Double-click Component 2
2 Under Definition set
a Hub to Hub
b Shroud to Shroud
c Blade to Blade
d Inlet to R1 to S2 Stage Side R1 Part 1
This is the rotor side of the frozen rotor interface so it is the inlet to
the rotor domain
e Outlet to Outlet
f R1 to R1 Periodic Side R1 Part 1
g R1 to R1 Periodic Side R1 Part 2
3 Click the Instancing tab then under Rotation you will see that the
Angle From is set to Instances in 360 the of Passages is set to 113
and the PassagesComponent issetto2 These settings are correct for
this component
4 Click Apply
5 Double-click Component 1
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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Flow in an Axial RotorStatormdashViewing the Results
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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Flow in an Axial RotorStatormdashViewing the Results
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
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6 Under Definition set
a Hub to Hub 2
b Shroud to Shroud 2
c Blade to Blade 2
d Inlet to Inlet
e Outlet to R1 to S2 Stage Side S2 Part 2 This is the stator side of the Frozen Rotor interface so it is the outlet
from the stator domain
f Periodic 1 to S2 to S2 Periodic Side S2 Part 1
g Periodic 2 to S2 to S2 Periodic Side S2 Part 2
7 Click the Instancing tab where you will see that Angle From is set to
Instances in 360 of Passages is 60 and PassagesComponent is 1
These are all correct for this component
8 Click Apply
9 As for the initial axial case the meridionalturbo surface will obscure part
of the plots you will be creating in the next steps In the Object Selector
uncheck the visibility for the Turbo Plotter Merid Surface
Creating a Turbo SurfaceMidwayBetween the
Hub andShroud
1 Click View Toward -X (by using the viewer icon drop-down menu)
and zoom in so that the geometry fills the Viewer
2 Make all existing plots invisible
3 Select Turbo gt Turbo Surface from the main menu bar
4 On the Geometry panel set
a Domains to All Domains
b Method to Constant Span
Constant span specifies a fractional distance from the hub (0) to the
shroud (1) In this case a plot is created at 05 (halfway between hub
and shroud) See Turbo Measurements on page 187 in the
document CFX-Post for more detailsc Value to 05
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 2930
Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 283
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5 On the Colour panel set
a Mode to Variable
b Variable to Pressure
c Range to User Specified
d Min to -12000 [Pa]
e Max to -8000 [Pa]6 Click Apply to create the turbo surface
Setting upInstancing Transformations
Next you will use instancing transformations to view a larger section of the
model The properties for each domain have already been entered during
the initialisation phase so only the number of instances needs to be set
1 In the Turbo Plotter make sure that Plot is set to Turbo 3D View
2 In the Instancing section of the form set of Copies for both domains
to 6 (For each domain click Apply after you set of Copies)
Creating a TransientAnimation
Start by loading the first timestep
1 Click Show Timestep Selector
2 Select Time Value 0
3 Click Apply to load the timestep
The rotor blades move to their starting position This is exactly 1 pitch
from the previous position so the blades will not appear to move
4 Turn off visibility for the Wireframe object
822019 Tut Axial Rotor Stat Or
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Flow in an Axial RotorStatormdashViewing the Results
Page 284 CFX-5 Tutorials
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5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 2930
Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 3030
Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 2830
Flow in an Axial RotorStatormdashViewing the Results
Page 284 CFX-5 Tutorials
Master Contents Master Index Help On Help
5 Position the geometry as shown below ready for the animation During
the animation the rotor blades will move to the right Make sure you
have at least two rotor blades out of view to the left side of the Viewer
They will come into view during the animation
6 Click Show Animation Editor
7 In Animation Editor click New
8 Use the Timestep Selector to load Time Value 00002124
9 In the Animation Editor click New to create KeyframeNo2
10 Highlight KeyframeNo1 then set of Frames to 9
11 Click Options and set Timestep to TimeValue Interpolation
Playing theAnimation
The animation now contains a total of 11 frames (9 intermediate frames plus
the two Keyframes) one for each of the available time values
1 On the Animation Editor form turn on Save Animation Movie
2 Click Browse nexttothe MPEG File box and then set File name to
an appropriate file name (ending inmpg)
3 If Frame 1 is not loaded (shown in the top right corner of the Animation
Editor) click To Beginning to load itWait for CFX-Post to finish loading the objects for this frame before
proceeding
4 Click Play Forward
bull It takes a while for the animation to complete
bull To view the MPEG file you will need to use a media player that
supports the MPEG format
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 2930
Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 3030
Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 2930
Flow in an Axial RotorStatormdashViewing the Results
CFX-5 Tutorials Page 285
Master Contents Master Index Help On Help
You will be able to see from the animation and from the plots created
previously that the flow is not continuous across the interface
This is because a pitch change occurs The relatively coarse mesh and the
small number of timesteps used in the transient simulation also contribute
to this The movie was created with a narrow pressure range compared to
the global range which exaggerates the differences across the interface
FurtherPostprocessing
You can use the Turbo Calculator to produce a report on the performance
of the turbine
1 Select Turbo gt Turbo Calculator from the main menu bar
2 Set Macro to Gas Turbine Performance
3 Set Ref Radius to 04575 and leave other settings at their default
values
4 Click Calculate
5 Click View Report
The values calculated are defined inPredefined Macros on page 158 in the
document CFX-Post
Next TutorialPrevious Tutorial
822019 Tut Axial Rotor Stat Or
httpslidepdfcomreaderfulltut-axial-rotor-stat-or 3030
Flow in an Axial RotorStatormdashViewing the Results
Master Contents Master Index Help On Help