CURS 2 3 Hydraulic Machines Construction

8/12/2019 CURS 2 3 Hydraulic Machines Construction

http://slidepdf.com/reader/full/curs-2-3-hydraulic-machines-construction 1/34

5 June 2014 1

5 June 2014 1

5 June 2014

CONSTRUCTION. Classification

HYDRAULIC MACHINES



5 June 2014 2

CONSTRUCTION

THE MAIN COMPONENTS OF TURBOMACHINES. THEIR

ROLE



Buidings.

The blades of the impeller areusually placed between two paralleldisks; one is fixed on the shaft (the

crown) and the other one thatcontains the inlet of the fluid (thering).

5 June 2014 3



The principle of operation

The fluid passes through the suctionpipe, gets into the rotor where akinetic energy is inculcated upon it,

which afterwards is converted intopotential energy in the spiral roomand in the discharge pipe. Some

centrifugal pumps are equipped witha stator with blades that have therole to convert the kinetic load into

pressure load and to direct the fluid.

5 June 2014 4



The components of centrifugal

pump

5 June 2014 5



the classification of turbo pumps and

the shape of the meridian suction of

their rotor

Hydrodynamic pumps or turbo pumps may be classified by thespecific rotation

or dynamic rapidity, that can beconsidered as the rotation of a pumpgeometrically similar with the given

one, which absorbs a power of 1 H.P.at a load of 1m:

5 June 2014 6



Classification

5 June 2014 7

Specific rotation ns androtation n measured with the

tachometer, obviously cannothave the same dimension.In order to classify the turbopumps we can also use theircharacteristic rotation orkinematic rapidity:



The turbopump theory

Hypotheses:

a) Between two consecutive

blades of the rotor of thecentrifugal pump, the flow ofthe fluid is stationary, in theshape of some streamlines thattake the curvature of the blade.

b) Inside the pump we don’thave hydrodynamic losses.

c) The rotor consists of aninfinite number of blades withnegligible thickness.

5 June 2014 8



The speeds

5 June 2014 9



The fundamental equation of turbo

machines, applied in the case of centrifugal

pumps can be obtained in several ways: a) by applying the theory of variation

for the moment of movementquantity (impulse)

b) by applying Bernoulli’s equationfor the relative movement betweenthe points 1 and 2.

5 June 2014 10



The fundamental equation of

turbo machines

a) by applyingthe theory of

variation for themoment ofmovementquantity

(impulse)

5 June 2014 11




turbo machines

b) by applyingBernoulli’s

equation for therelativemovementbetween the

points 1 and 2.

5 June 2014 12




turbo machines

5 June 2014 13



5 June 2014 14

CONSTRUCTION OF THE ROTOR(IMPELLER)



5 June 2014 15

Construction of hydraulic machines

The cinematics of movement in turbomachines

kjit



5 June 2014 16

The cinematics of movement inturbomachines

a. The representation of parameters’movement in the rotor in the fixed referencesystem

b. The representation of parameters’movement in the rotor in the mobile referencesystem

O1 x 1y 1 z 1

Oxyz

k jit x



5 June 2014 17

CONSTRUCTION

The relationship between kinematic elements



5 June 2014 18

CONSTRUCTIONc. Customize cinematic parameters of flow to movement in the rotor case

taking into account the following assumptions:

- It is acceptable that the z axis is along the machine axis, and the distancebetween the origins of the two systems is constant

- The reference cell is rotating rotor machine

- the fluid is considered ideal

- fixed reference system and the mobile is convenientlychoose

•accepted to represent the cylindrical coordinate system(R, , z);

- accepted to represent the cylindrical coordinate system(R, , z)



5 June 2014 19

Following expressions are obtained



5 June 2014 20

The hypothesys of potential absolutemovement



5 June 2014 21

d. Velocity triangles



5 June 2014 22

Velocity trianglesInlet and outlet



5 June 2014 23

Correlation between functional user request parameters (flow rate Qn, headHn ) and constructive parameters of the machine.It has adopted a number of simplifying assumptions about themachine and fluid

Peculiarities of functioning of hidropneumatice specific machines of a certainfluid transported or of a specific sense of energy transfer:

differences that may arise in the case of liquids and gases transports

differences that may arise in the event of a transfer of energy in forcing andworking machines

The laws governing the flow in turbomachines



5 June 2014 24

Flow rate and load of turbomachines in the

assumptions: the ideal, ideal fluid machine





5 June 2014 26

It is observed that, for the sake of axial symmetry

mişcarea are simetrie axială, adică v rm1, v rm2 şi

the movement has axial symmetry, i.e. Vrm1, vrm2 and the density,It cannot change over the surfaces S1, S2



5 June 2014 27

Theoretical flow of theoretical rotor

If fluid considered compression connectors (blowers and compressors)

rs)

If the fluids are considered incompresibile



5 June 2014 28

Theoretical load (head) of the rotor in theory

Observations:-the movement of the fluid in the impeller is considered permanent

- The absolute speed are expressed



5 June 2014 29

-These cross-sectional surfaces S1, S2, have axial symmetry,and their normals n1, n2, passing through the axis of the machine

-The fluid is ideal, that means the relative movement is tangent to the surface

-SI, SE, zSz

- the forces of gravity for reasons of symmetry, have the application directlyon the rotor axis

e pressure orces e u ac s on mpe er crowns e ro ors are equa an



5 June 2014 30

p p qopposite forces sign with these areas acting on the fluid, producing hydraulictorque

The expression of angular momentum theorem becomes

The components of the moment after the R and φ directions are taken fromshaft of machines, so the Mz is received from your machine, and drivethen, rotary, the fluid conveyed



5 June 2014 31

Control surface has axial symmetry

Using cylindrical coordinates for expressions of cinematical parameters

For reasons of symmetry, axial surfaces S1 and S2,the values of the density and speed remain constant

So



5 June 2014 32

Taking into account the hypothesis ofideal fluid

But so:

The Basic Law of the turbomachines (turbop



5 June 2014 33

Conclusionsfrom the fundamental theorem of turbomachines expressions

1. Conclusions on the basisof the expression

2. Conclusions on the basis

of the expression

CONSTRUCTIA MASINILOR HIDRAULICE



5 June 2014 34

CONSTRUCTIA MASINILOR HIDRAULICE

The extent of reaction

We distinguish the following types of machines depending on the degree ofreaction

R = 1 - pure reaction machines

- reaction machines

- action machines

- Pure action machines

Documents

CURS 2 3 Hydraulic Machines Construction