UTSR Presentation Heat Transfer Developmentincreased jump cooling flow, or to improve the cycle performance. 19 Case Change fromPrevious T250 Phase 4 Engine Version Low Risk CoolantFlow

Caterpillar Confidential - Yellow

UTSR Presentation

Heat Transfer Development

Robert LaFasoMentor: Yong Kim

Group Manager: Hee Koo MoonDepartment Manager: Dan Burnes

General Questions to All Manufacturers

Caterpillar Confidential - YELLOW

Overview

Personal Background Projects at Solar Turbines

Hot Gas Ingress Model w/ Finesse T250E 2-D Steady State Thermal Model w/ ANSYS T250E Jump Cooling w/ ANSYS

San Diego Fun!

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Hometown: Cheyenne, Wyoming School: University of Wyoming

Major: BS Energy Systems Engineering Minor: Mathematics Est. Grad. Date: Spring 2017

Extra Curricular Activities Student Government Tau Beta Pi Sigma Nu Fraternity

Personal Background

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Overview

Personal Background Projects at Solar

Hot Gas Ingress Model w/ Finesse T250E 2-D Steady State Thermal Model w/ ANSYS T250E Jump Cooling Change Study w/A ANSYS

San Diego Fun!

4



Hot Gas Ingress Model w/ Finesse

Goals Use Finesse to simulate ingress and generate reliable hot gas

ingress predictions Generate Taw and HTC to be applied to 2D thermal model Build a model that will allow for the minimization of disk purge

cooling flows About Finesse Finesse is software that solve 1-D Fluid Flow Networks with

portions designed specifically for turbomachinery secondary flow

It is an iterative solver that takes user input connectors and BC and solves to minimize mass imbalance and calculate mass flow rate

Uses Solar Turbine’s proprietary DCAT (Disk Cavity Analysis Tool) connector to simulate flow through rotating disk cavities.

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Ingress Overview Hot air from main flow path enters disk cavity between rotor

and stator. Bleed air is used to purge the disk cavity of the ingress gas Ingress is driven by pressure variation in the main air flow

path

Figure 1: Circumferential Pressure distribution that drives ingress [1] Figure 2: Schematic of Hot Gas Ingress [2]

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Ingress Modeling The ingress and egress paths are modeled as short orifices

connecting disk cavities creating flow loops. Flow loops are built of orifice connectors and DCAT

connectors. Previous research indicates that ingress tends to hug the

stator walls. This was the basis for the cell rotation direction.

Figure 3: Finesse Model and its Analogous Physical System

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Important Parameters Ingress is quantified by effectiveness Ingress area ratio describes the relationship

between the ingress and egress flows throughthe smallest gap between the flow discouragers

Discharge coefficients of the ingress and egress orifices are a function of these two parameters.


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1 1

Figure 4: Ingress and Egress area schematic



Arizona State Disk Cavity Rig and Data Report by ASU published in 2015 reported

ingress levels and mass flow rate at 4 flow rates Manipulated until the effectiveness calculated

in Finesse matched data from published report Demonstrated an exponential relationship

between calculated and the given purge massflow rate


Figure 6: ASU Experimental Setup [1]

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rA = 0.5000e-1.5927x

R² = 0.9865

0.0

0.1

0.2

0.3

0.4

0.5

0.0000 0.5000 1.0000

Ingr

ess

Are

a R

atio

Non-Dimensional Purge Flow Rate Figure 5: rA and Purge flow Relationship



Sensitivity Testing Looked into the effect different modeling methods had on the

results. Adjusted parameters included: Number of cells Rotational mass flow Orifice area for orifices that connect the cells Rotation speed Discharge coefficient for orifices that connect the cells


Figure 8:Ingress Level Sensitivity to Number of cells

Figure 9: 3 Cell Ingress model or Titan 130

Figure 7: 4 Cell Ingress Model ofTitan 130

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Sensitivity Testing Helped to define consistent settings that are robust and

accurate and addressed issues with: Rotation direction not conforming to experimental results where the

ingress flow path tends to hug the stator. Iterative solutions not converging quickly, monotonically, or at all Merging the ingress model with existing secondary flow Finesse

models resulting in crashes

Figure 10: Finesse Error Display Showing an Unstable Converging System. The error should

ideally decrease monotonically Figure 11: Ingress model flow network with the top

cell rotating in the incorrect direction.

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Modeling Comparison Compared the output data of the ingress model to the data for

current modeling techniques New method to compares favorably to experimental CO2 data

Percent error is ~15% New method caused discontinuities because of mixing at nodes By design, the new method produces a hotter stator-side wall and

a cooler rotor-side wall.

Figure 12:Table of Experimental CO2 Ingress Data and Ingress Data from the Finesse Ingress Model

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LocationLow Purge Flow High Purge Flow

Experimental Finesse Experimental FinesseDisk Cavity Midpoint 16.3% 16.6% 7.3% 7%

Disk Cavity Bottom 14% 11% 5.6% 3.2%




Modeling Comparison Cont. (Data for T250E Stg 1)

Figure 13: Plots comparing the data produced by the current modeling method (Blue) of modeling disk cavities with the data produced by the new ingress modeling method (Red)

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Overview


Hot Gas Ingress Model w/ Finesse T250E 2-D Steady State Thermal Model w/ ANSYS T250E Jump Cooling Change Study w/ ANSYS

San Diego Fun!

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T250E 2-D Thermal Model w/ ANSYS

Goals Utilize an existing ANSYS 2-D Transient model built by Agilis

Engineering and apply the boundary HTC and adiabatic wall temperature boundary conditions generated by the Finesse network

Solve the ANSYS 2-D Transient Model for the full load steady state metal temperature in the disk cavities.

Updating the ANSYS Model The ANSYS model was not built to have the HTC and Taw defined

for each surface element Previous temperature boundary conditions were from fluid elements Previous model applied same temperature to rotor and stator walls Modified the model to accept a manually input Taw as the bulk

temperature for convective heat transfer calculations. Unique Taw and HTC for each finite element

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Results Application of the new ingress model derived boundary

conditions resulted in changes that match expected results. Strongest decrease of temperature occurred at the leading

edge platform tip of both the stage 1 rotor and stage 2 stator Temperature increases were stronger for elements at lower

radial positions.

T250E 2-D Thermal Model w/ ANSYS

Component Approximate Change Due to Modeling Methods

Stage 1 Cavity Stator Side +50◦ to +250◦ F Stage 1 Cavity Rotor Side -50◦ to +100◦ F Stage 2 Cavity Rotor Side +50◦ to +200◦ F Stage 2 Cavity Stator Side 0◦ to + 50◦ F

Figure 14: Changes in metal temperatures from implementing the new ingress model

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Overview



San Diego Fun!

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T250E Jump Cooling w/ ANSYSGoals Utilize the new ingress model to more accurately estimate the

temperature of the Stage 1 Nozzle of the T250E Model impact of jump cooling flow increases Jump Cooling Overview Compressor air injected directly upstream of the 1st stage

nozzle. Used to cool the first stage nozzle which experiences the

highest temperature flows Has a lower impact on cycle performance than other cooling

methods since jump cooling air is still is processed by the full turbine section.

Effectiveness is given by

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Two Cases Analyzed Med/High cases utilizes less bleed air for cooling the stage 1

nozzle cavity. This gives more air available for other cooling uses, such as

increased jump cooling flow, or to improve the cycle performance.

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Case Change from Previous T250 Phase 4 Engine Version

Low Risk Coolant FlowModerately Decreased 1st Nozzle inner

cavity pressure cuts inner rail leakage flow to stage 1 disk cavity.

Med/High Risk Coolant Flow

Additional decrease in cavity pressure yields a higher leakage flow reduction but

allows more ingress.

Figure 15: Table of Proposed Secondary Cooling Changes

T250E Jump Cooling w/ ANSYS



Changed Model to have Increased Jump Cooling Provided with experimental data for jump cooling effectiveness Calculated new effectiveness at new jump cooling flow rates for

the new proposed changes by interpolating experimental data New effectiveness was used to back out a new BC

Case Outer JC Change

Inner JC Change

Low Risk +.3% of InletFlow Rate

+.2% of Inlet Flow Rate

Med/HighRisk



Figure 17: Proposed Changes to Jump Cooling

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Figure 16: Jump Cooling Effectiveness as a function of cooling flow rate




Results Changes to jump cooling resulted in hot spot temperatures

more comfortably below the recommended temperature maximum of 1750°F

Extra jump cooling flow allows the Med/High risk case to have a lower hot spot temperature even with a hotter baseline temperature that resulted from less cooling air leaking into the disk cavity

Case Hot Spot Temperature

Low RiskBaseline 1711°F

w/ Increased JC 1691°FChange -20°F

Med/High Risk

Baseline 1719°Fw/ Increased JC 1684 °F

Change -35°FFigure 18: Results of Jump Cooling Change Study 21




Overview



San Diego Fun!

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San Diego Fun

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Barbara StanleyBernhard Winkelmann

John MasonMark NovaresiJamie Rhome

Jorge Gonzalez AyalaCharmaine GaryStefania Dzwill

Charmaine GaryReina Maldonado

Noemi Victoria

Thank you!

Dan BurnesHee Koo Moon

Yong KimKevin Liu

Hasan NasirNeil JordanJeff Carullo

Juan YinDan LancasterAnthony FlettJessi Geshay

2016 Summer Interns

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Robert LaFaso(307) 287-3833

[email protected]

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Sources:

[1] R. P. Roy, J. Balasubramanian & M. Michael, Solar Turbines –Disk Cavity Research, Progress report #5 (Experiment Set I –Config. 1B), September, 2015

[2] Scobie JA, Sangan CM, Michael Owen JJ, Lock GD. Review of Ingress in Gas Turbines. ASME. J. Eng. Gas Turbines Power. 2016;138(12):120801-120801-16. doi:10.1115/1.4033938.

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Documents

UTSR Presentation Heat Transfer Developmentincreased jump cooling flow, or to improve the cycle performance. 19 Case Change fromPrevious T250 Phase 4 Engine Version Low Risk CoolantFlow