proceedings of 27th european space thermal analysis …evaluation of heat transfer parameters from...

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Appendix C

Evaluation of Heat Transfer Parameters from CFD for Use inTMM in Case of Gas Convection in Vented Cavities

Christian Wendt(Astrium Space Transportation, Bremen, Germany)

27th European Space Thermal Analysis Workshop 3–4 December 2013

34Evaluation of Heat Transfer Parameters from CFD for Use in TMM in Case of Gas Convection

in Vented Cavities

Abstract

The analysis of the convection in Ariane 5 launcher’s vented cavities on ground and during ascent isimportant for the thermal control of the equipments and of the propellants during flight phase. For theaccording analysis of the upper stage, a lumped parameter Thermal Mathematical Model (TMM) hasbeen established within ESATAN.As an input, heat transfer parameters (HTPs) have been derived from two related Computational FluidDynamic (CFD) analysis cases, the so called hot and cold case. The methodology for evaluation of theseHTPs from the CFD analysis is described for one and more gas nodes based on steady state results. For arepresentative launcher cavity with laminar/turbulent buoyancy influenced flow, a comparison is providedbetween the TMM results and the CFD results obtained with the commercial tool ANSYS Fluent. Exactagreement is achieved between TMM and CFD for the hot and the cold case. Deviations for the analyzedintermediate cases turned out to be less than 5K in case of a one gas node TMM and less than 3K in caseof a seven gas node TMM.


Evaluation of Heat Transfer Parameters from CFD for Use in TMM in Case of Gas Convection in Vented Cavities

27th annual European Space Thermal Analysis Workshop, 3rd & 4th Dec. 2013, Noordwijk

C. Wendt, Astrium Space Transportation, Bremen, Germany

• Introduction

• Background

• Description of Methodology

• Test Case

• Conclusion & Outlook

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Page 2

Introduction: Example A5ME Ground Phase

LOXLH2

EBS Cavity with N2 venting(or He venting)

ETF Cavity with N2 venting

Interstage Cavity with N2 venting

Evaluation of Heat Transfer Parameters from CFD for Use in TMM in Case of Gas Convectionin Vented Cavities 35


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Page 3

Background: Check of CFD with Cryo-Tests

N2 vented cavity with a simplified typical geometry

Variable temperature of heat exchanger to realize several test cases

Good agreement betweenCFD and test

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Method: Approach for HTPs from CFD


in Vented Cavities


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Method: Gas/Wall Heat Transfer GLs from CFD

hotiw

hoti

hotiwhot

iw TTQ

GL,

,,

coldiw

coldi

coldiwcold

iw TTQ

GL,

,,

)(,,,,

coldinincold

inhotin

coldiw

hotiwcold

iwiw mmmmGLGL

GLGL

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Page 6

Method: Gas/Gas Heat Transfer GFs and Qs from CFD

)()()()(

),( ,,,,

coldi

coldjijcold

icoldj

hoti

hotj

coldig

hotigcold

igjiig TTTTTTTT

QQQTTQ

)()(,,

coldi

coldj

hoti

hotj

coldig

hotig

i TTTTQQ

GF

)()()(

,,,

coldi

coldjcold

icoldj

hoti

hotj

coldig

hotigcold

igi TTTTTT

QQQQ



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Page 7

Method: Venting Inlet/Gas Heat Transfer GFs and Qs from CFD

)()()()(

),,( ,,,,

coldi

coldin

coldiniinincold

icold

incoldin

hoti

hotin

hotin

coldig

hotigcold

igiininig TTmTTmTTmTTm

QQQTTmQ

)()(,,

coldi

coldin

coldin

hoti

hotin

hotin

coldig

hotig

ini TTmTTmQQ

mGF

)()()(

,,,

coldi

coldin

coldincold

icold

incoldin

hoti

hotin

hotin

coldig

hotigcold

igi TTmTTmTTm

QQQQ

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Page 8

Test Case: EBS Cavity

DescriptionTemperature

Wall 1[K]

Temperature Wall 2

[K]

Mass Flow Temperature

[K]

Mass Flowrate up

[g/s]

cold 200 220 294 60hot 210 250 314 80


in Vented Cavities


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Page 9

Test Case: CFD Results for Cold + Hot Case

cold case

hot case

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Page 10

Test Case: TMM



Test Case:Comparison between TMM and CFD

Case Nr.

Temperature Wall 1[K]

Temperature Wall 2 [K]

InletTemperature[K]

Mass Flowrate up [g/s]

1 205 235 304 70

2 205 235 314 60

3 205 235 294 80

4 195 210 274 60

5 215 260 334 80

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Page 12

Test Case:Comparison between TMM and CFDOne Gas Node Model

-4

-3

-2

-1

0

1

2

3

4

5

cold hot 1 2 3 4 5

Case

∆Te

mpe

ratu

re [K

]

∆Twall average [K]Max |∆Twall| [K]∆Tgas [K]

Seven Gas Node Model

-4

-3

-2

-1

0

1

2

3

4

5

cold hot 1 2 3 4 5

Case

∆Te

mpe

ratu

re [K

]

∆Twall average [K]Max |∆Twall| [K]∆Tgas average [K]Max |∆Tgas| [K]


in Vented Cavities


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Page 13

Conclusion & Outlook

• Methodology for transfer from CFD to TMM explained for vented cavities

• Comparison beween TMM and CFD showed good overall agreement for EBS Cavity for the One Node and Seven Nodes Model as well: Seven Gas Node Model about ~40% better than One Gase Node Model

• Method is currently enhanced to include time dependency, as needed e.g. for propellant stratification phenomena

One Node Model Seven Node Modelmaximum temperature deviation ~4K ~2.5Kmaximum LH2 heat flux deviation ~1% ~0.5%



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