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UTSR Summer Internship: Siemens EnergyDavid Billups / September 13, 2015

Restricted © Siemens AG 2015 All rights reserved.

2015-09-13 David Billups / PG GT LGT EN MT 1 2

Table of Contents

• Validation of StarCCM+ V10.04.009 3

• CFD* Study of IDC** Cavities 16

• V-Shaped Dimples 21

• IDC S1 Model 29

• Case 1 32

• Case 2 36

• Case 3 40

• Case 4 44

• Experimental Impingement Work 51

• Conclusions 58

* Computational Fluid Dynamics ** Internal Duct Cooling



Validation of StarCCM+ Version 10.04.009David Billups / August 2015

2015-08-06Page 3 David Billups / PG GT LGT EN MT 1 2




StarCCM+ Validation

Content

• This Validation required the analysis a case study. The results obtained with

the new version of StarCCM+ would be compared to those from the previous

version. The two case study was:

• Han ‘84 – Periodic CFD models for fast simulation

Purpose

• By comparing new results to previously calculated and understood solutions,

we are able to assess the performance of the new StarCCM+ code.



StarCCM+ Validation

Han ‘84



StarCCM+ Validation

Han ‘84 Case Study

Version 10.02.010 Version 10.04.009

The convergence history shows much less variation in the new solution, however both codes converge to

similar magnitudes.




Velocity Scalar


The velocity scalar results are nearly identical.

Version 10.02.010 Version 10.04.009 Percent Difference

Friction Factor 0.0347023 0.0348463 0.415%




Temperature Scalar


The temperature distribution is nearly identical.


Smooth Wall Temp (K) 342.875 343.042 0.0487%

Ribbed Wall Temp (K) 337.397 337.256 0.0418%




Nusselt Number


The Nusselt number results are nearly identical, showing only an 0.137% difference in average Nu.


Average Nu 206.283 206.565 0.137%



StarCCM+ Validation

Conclusions

Based on the results obtained for the Han ‘84 case, it was observed that there is very little difference in the

solutions produced by StarCCM+ Version 10.04.009 and past versions.

Slightly better convergence results obtained for the Han ‘84 case.

Indiscernible differences in Nusselt number.

StarCCM+ Version 10.04.009 is deemed suitable for production use.



CFD Study of IDC CavitiesDavid Billups / September 2015





CFD Study of IDC Cavities

Purpose

In experimental literature, dimples have been found to produce

• 2-3 times the heat transfer capability of a smooth channel

• 1-4 times the friction factor of a smooth channel

Ribs have been shown to produce

• 2-5 times the heat transfer of a smooth channel

• 10-20 times the friction factor of a smooth

[1] Brown, C. P., Wright, L. M., & McClain, S. T. (2015). Comparison of Staggered and In-Line V-Shaped Dimple Array

Using S-PIV. Proceedings of ASME Turbo Expo 2015: Turbine Technical Conference and Exposition.

Validate experimental studies of cavities with StarCCM+



V-Shaped Dimples

GT2015-43499

Summary of Experimental Study - Flow

Researchers at Baylor University used SPIV to analyze the

secondary flow characteristics at each of the x/Dh locations

specified.

• For presentation of flow characteristics, the authors

non-dimensionalized velocity by “average core velocity”

– this ambiguous value made it impossible to exactly

replicate the PIV results.



V-Shaped Dimples

GT2015-43499

Summary of Experimental Results – Heat Transfer

The researchers performed a steady state heat transfer study using

thermocouples placed at the blue diamonds.

• The data shows that the In-Line geometry outperformed the Staggered

geometry, but both produced 1.5-1.8 times larger Nusselt number than that

produced in a smooth channel.

• Heat Transfer measurements were not included, thus it is impossible to

replicate the study

Model using same conditions as previous rib geometry

[1] Brown, C. P., Wright, L. M., & McClain, S. T. (2015). Comparison of Staggered and

In-Line V-Shaped Dimple Array Using S-PIV. Proceedings of ASME

Turbo Expo 2015: Turbine Technical Conference and Exposition.



V-Shaped Dimples (GT2015-43499)September 2015





V-Shaped Dimples

In-Line Case

In-Line Geometry

• Consecutive rows of 3 dimples

• Equally spaced in X and Z on centers

Mesh

Mesh Quality

ParameterAcceptable

Limit

Model Limit

(Worst Case)

# of Cells outside

Acceptable Limit

Percentage outside

Acceptable Limit

Face Validity > 0.9 1.0 0 0.00

Cell Quality> 0.01 0.05 0 0.00

Volume Change > 1E-4 6.43E-4 0 0.00

Skewness Angle

[deg]< 85 85 0 0.00

Total Number of Cells 7,662,078



V-Shaped Dimples

In-Line

Average Nusselt number is low

relative to ribbed features.

Avg Nu=145.929

Velocity Streamlines show exactly

what is found in the experimental

study, which is that the V-Shaped

dimples direct flow outwardly from

the center of the dimple.

The velocity profile shows low flow

into the dimples.



In-Line Dimple Array

Secondary Flow

Experimental Results (Re=37k) CFD Results (Re=70k)



V-Shaped Dimples

Staggered Case

Staggered Geometry

• Alternating rows of 2 and 3 dimples. Each dimple is

centered between the two in front.

• Same dimensions as In-Line case

Mesh

Mesh Quality

ParameterAcceptable

Limit

Model Limit

(Worst Case)

# of Cells outside

Acceptable Limit

Percentage outside

Acceptable Limit

Face Validity > 0.9 1.0 0 0.00

Cell Quality> 0.01 0.05 0 0.00

Volume Change > 1E-4 6.42E-4 0 0.00

Skewness Angle

[deg]< 85 85 0 0.00

Total Number of Cells 7,662,078



V-Shaped Dimples

Staggered

Average Nusselt number is slightly

less than the V-Shaped In-Line

case.

Avg Nu=128.454

Velocity streamlines show what is

found in the experimental results

which is that the staggered pattern

redirects flow toward the center of

downstream dimples.

The velocity profile again shows

that there is little flow within the

dimples.



Staggered Dimple Array

Secondary Flow

Experimental Results (Re=37k) CFD Results (Re=70k)



V-Shaped Dimples

Conclusions

• A discrepancy exists between the heat transfer capabilities seen in the CFD results and the experimental

results.

• Comparisons to experimental study are abstract (Experimental Re=37k, CFD Re=70k)

It would be worthwhile to run some cases at varying Re just to be sure that the CFD flow

results match the experimental PIV results.



Error

V-Shaped Dimples

The models geometrically represent that of the experimental setup, however,

without the correct information, the models could not be run in the same

conditions that were present experimentally, thus it was impossible to

numerically validate the experiment. At this junction, the models were run

under the same conditions as a previously studied ribbed channel. This

ribbed geometry is protected as Siemens Energy proprietary information. The

dimensions of this channel are larger than the V-Shaped dimple channels.

Due to this difference in dimension, the characteristic length in Reynolds

number, which is defined as half the width of the channel, was much smaller

for the V-shaped cases, thus they were subject to much higher velocities. It is

the result of this that you see much higher velocity magnitudes in the V-

shaped velocity scalar plots. For these reasons, drawing any conclusions

from the V-shaped models presented in this study is incorrect.



Experimental Impingement WorkSeptember 2015





Entrainment Investigation

Issues

There were some inconsistencies in the data which were thought to be a

result of entrainment.

Plan of Action

• Insert TC’s near the jet exit to get a better measurement of jet exit

temperature

• Build a vertical rake at the edge of the skirt to capture the temperature

profile along the height of the rig.

• Build a horizontal TC rake radially outward from the center such that a

radial temperature distribution can be obtained.




Jet Exit Temperature

Experimental Setup

• Placed multiple TC’s around and in the jet exit

• Jet Exit temp previously was assumed to be same

as plenum temp

Results

Re=20k Difference [%]

z/D=1 0.78

z/D=6 1

Re=40k

z/D=1 2.25

z/D=6 0.89

Re=60k

z/D=1 1.11

z/D=6 4.08

Re=80k

z/D=1 2.73

z/D=6 5.19

Difference in Nu from test matrix vs. jet temp characterization tests




Vertical TC Rake

Experimental Setup

• Rebuilt vertical TC rake to get better data for CFD

entrainment prediction

• Spaced 10 TCs evenly across z/D=3 PLENUM

TC RAKE

TC DIRECTION

SKIRT

Z/D = 3

ALL

EQUALLY

SPACED BY

0.33D

SKIRT

COPPER

13D

10 TC’S IN

TOTAL

SIDE

VIEW

TOP

VIEW




Vertical TC Rake

Conclusions

• Variation in Temp along the height of the TC rake is within TC variation (±0.4 °C), but we are seeing

consistently higher results from jet temp by ~2.25% (7°C)

0

0.5

1

1.5

2

2.5

3

3.5

1.00% 1.50% 2.00% 2.50% 3.00%

z/D

Vert

ical

Lo

cata

ion

Percent Difference in Rake TC and Jet Exit TC Measurements

Temp Profile at r/D=13 (Run 1)

Re=20k

Re=40k

Re=60k

Re=70k

0

0.5

1

1.5

2

2.5

3

3.5

1.00% 1.50% 2.00% 2.50% 3.00%

z/D

Vert

ical

Lo

cata

ion

Percent Difference in Rake TC and Jet Exit TC Measurements

Temp Profile at r/D=13 (Run 2)

Re=20k

Re=40k

Re=60k

Re=70k




Horizontal TC Rake

Experimental Setup

• 10 equally spaced TC’s

• Located 20mm above surface

• Shielded from radiation from the copper plate by

wooden dowel

Z/D = 3

TC TIPS ARE

20MM FROM

SURFACE

SKIRT

10 TC’S IN

TOTAL

COPPER

5D

3D




Horizontal TC Rake

Conclusions

• At higher z/D, the core temperature of the jet is more effected by entrainment

• Re=20k data was taken after Re=80k, so the rig was hot which probably explains the variation in Re.

• At smaller z/D, recirculation temperature is higher.

25

26

27

28

29

30

31

32

0 0.5 1 1.5 2 2.5 3 3.5

Tem

pera

ture

(°C

)

r/D Radial Distance From Center

Temp Profile at z/D=0.66

z/D=3 Re=20k

z/D=6 Re=20k

z/D=3 Re=80k

z/D=6 Re=80k



Moving Forward

Succeeding Work

IDC

• The second alternating rib/cavity case could be run and analyzed

• The V-Shaped dimple cases should be run disregarding heat transfer at the

same flow conditions as the experimental study. The V-Shaped dimple cases

should be rebuilt to better match the geometry of the ribbed model that they will

be compared to.

Impingement

• The team at the Siemens Energy Center (SEC) is working to finish

troubleshooting this rig and move on to new investigations.

Thank you to those who helped guide me along the way!



David Billups

UTSR Intern

PG GT LGT EN / Orlando / MT 1 2

4400 N. Alafaya Trail

Orlando, FL 32826

Mobile: (804) 767 0690

E-mail:

[email protected]

[email protected]

Thank You!

siemens.com/energy

mailto:[email protected]

mailto:[email protected]

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