conjugate heat transfer analysis of nasa c3x film cooled...

L. Mangani

MaschinentechnikCC Fluidmechanik und Hydromaschinen

Hochschule LuzernTechnik& Architektur

Technikumstrasse 21, CH-6048 HorwT +41 41 349 33 11, F +41 41 349 39 60

e-mail: [email protected]

Fifth OpenFOAM Workshop, June 21-24 2010, Gothenburg, Sweden

CONJUGATE HEAT TRANSFER ANALYSIS OF

NASA C3X FILM COOLED VANE

Lucerne University - SwitzerlandConjugate Heat Transfer Analysis Of Nasa C3x Film Cooled Vane

T&A Luca ManganiFifth OpenFOAM Workshop, June 21-24 2010, Gothenburg, Sweden

Presentation outline

2/21

• Background-State of the Art

• Heat Transfer in Turbo-Gas engine

• Developments for heat transfer analysis in

turbomachinery

• Present contribution

• Results and discussion

• Conclusions



Heat Transfer in Turbo-Gas Engine

3/21

• Heat transfer analysis of turbomachinery aims at:

– Increasing turbomachinery performance:

Efficiency increases with high inlet temperature

– Extending machine working life

– Preventing catastrophical damages

• Cooling systems of:

– Rotor blades

– Stator vanes

– Combustors

– Turbine endwalls

– Stator-rotor cavities

0

' '

w f

y=

Tq = k

y




T&A Luca Mangani

OpenFOAM™ Developments

Steady-State all-Mach algorithm

• Steady-state: no artificial time derivative included

• All-Mach flows

• Pressure correction based

Compressible turbulence models

• Low-Reynolds k-ε, k-ω SST, Two-Layer, automatic wall treatment, thermal wall function, anisotropic eddy viscosity

Mangani

Phd thesis 2007

Bianchini

Master thesis 2007

Tools specific for turbomachinery blades and CHT

• Fluid Structure Interaction, Radial equilibrium, total energy equation, rotating reference system

Mangani et al.

ETC 09

ASME IGTI 2008

ASME IGTI 2009

Mangani et al.

ASME-JSME 2007

Mangani

Phd thesis 2007

4/21



OpenFOAM™ Applications & Validations

• Heat Transfer in Turbomachinery devices:

– Turbine trailing edge internal cooling ducts with ribs, pedestals and pins [IGTI 2008, ETC 2009]

• Impingement cooling system devices:

– Film & effusion cooling systems [IGTC 2007, IGTI 2009]

• Subsonic and transonic real engine rotor blades:

– Stator rotor cavity systems [IGTI 2008]

• Conjugate Heat Transfer:

– Internally cooled stator vane [ETC 2009]

– Film cooling: Experimental setup [IGTI 2009]

5/21



Present contribution

6/21

• Energy equation solved in terms of temperature (static or total)

• Convective-diffusive equation degenerates into Fourier equation in case of null fluxes – same matrix for solid and fluid domain

• Mutual influence coefficients calculated imposing continuity of heat flux across the boundary

• The temperature values are calculated in both side with the generic grid interface boundary criteria

. .. .

1 11

sf

f w s w

f s

s s sf f f

f s s f

w s fw ss s sf f fs s

f s s f s f

E x tra d ia g C o e ffD ia g C o e ff

kkT T T T

y y

k T kk T k

y y y yT T T T

k k kk k ky y

y y y y y y

Developed algorithm for Conjugate Heat Transfer with Generic Grid Interface




T&A Luca Mangani

7/21


•Multiple implicit coupling - ghost cell mechanism

•Contribution of ghost cell calculated via cell-to-cell addressing and weighting factors αi

•Weighting factors based on face overlapping areas

– No explicit coupling between solid and fluid (too slow)

– Needed implicit coupling

Implicit coupling is guaranteed by a special boundary based on couplePatch

– Applied also to Total Energy Equation

– Redefinition of the members valueInternalCoeffs, gradientInternalCoeffs etc..

,1

f p p p i n i

i

w w

,i o i fpA A

,n i n iC C

Domain 1

Domain 2Non conformal interface

p

n1 n2

Generic grid interface boundary criteria



• 4-Equations turbulence model k-ε-v2-f

– Starting model [Lars Davidson et al. 2003]

Far way wall correction for v2 production term

– Added realizability constraint for the turbulent time and length scale [Lien et al., Sveningsson]


8/21



Present contribution: Test Cases

• Flat plate thermal bounday layer

– Heat transfer coefficient distribution along the stream-wise direction

• Axial symmetric impinging jet with wall heat flux

– Nusselt number distribution along the radius

9/21



Results: Film Cooled NASA C3X Vane

• Numerical model simulates experimental setup of Hylton et al.1988.

• NASA-C3X Film and internally cooled linear cascade

– Consists of a stainless steel blade.

– Internally cooled by ten radial channels.

– Three plenums are implemented feeding:

– Two rows of pressure side filmcooling holes.

– Five rows of leading edge shower head holes.

– Two rows of suction side film cooling holes.

10/21



Results: Computational Domain

• Following the work of [Garg et al.] the computational span, is only a part of the real span

• The spanwise pitch domain is 7.5d, where d is the diameter of the holes

• Periodic boundary conditions are imposed due to shower-head injection on the ends of the computational span

Periodic

Plenums

Cooling channel

Periodic

Film cooling holes

Shower Head

11/21



Results: Computational Grid

• Main flow mesh is the main challenge– Previous work by [Garg et al. 95]

No grid for the plenum and duct holes

– Previous work by [Ledezma et al. 08]

ANSYS CFX Tetra mesh fluid-fluid GGI interface at film cooling hole exit

– Present work:

Fully Hexa structured mesh with multi block strategy, GridPRO™

No GGI fluid-fluid interface between the flow path mesh and film cooling hole exit

11’000 Blocks was used

12/21



Results: Computational Grid

• GGI solid-fluid interface between flow, radial cooling channel path and blade

13/21



Results: Pressure distribution

• No pressure profiles data from [Hylton et al. 88]

• Experimental pressure distribution only present in [Garg et al. 94]

• Running code #44155

• Turblence Models used:

– Spalart-Allmaras, k-ω SST, k-ε Two-Layer, v2-f

[Garg et al. 94] Present work

14/21



Results: Heat Transfer Coefficient

• The reference run code is #44344

• Turbulence models used:– Spalart-Allmaras, k-ω SST, k-ε Two-Layer, v2-f

• No data given for about 25% from leading edge

• No CHT simulation: Average wall temperature imposed based on exp.

HTC=Q/(Tw-T0)

15/21




• BC for the radial cooling channel based on [Ledezma et al. 08]

• Turbulence Models used:– Spalart-Allmaras, k-ω SST, k-ε Two-Layer, v2-f

• No data given for about 25% from leading edge

• CHT simulation

• Wall temperature and HTC evaluation vs. experiment

16/21




• Results analysis:

– Wall temperature profile in good agreement with experiment

– Less agreement for the HTC profile than wall temperature

Three temperature problem

Taw should be preferred as reference temperature for scaling the heat flux

HTC=Q/(Tw-T0)

CHT: Temperature CHT: HTC

NO CHT: HTC

17/21



Results: Contour Maps

• Temperature maps

• Sink effect of the radial cooling channel

18/21



Results: Streamlines

• Shower head jets influence downstream film cooling

– Lift effect in film cooling in pitch-wise direction

– SH influence more the pressure side film cooling development

19/21



Conclusions

• Conjugate heat transfer simulation of a representative first stator cooling vane with a turbulence models assessment was simulated

• OpenFOAM has been improved to predict heat transfer phenomena in gas turbine blade cooling

• Generic Grid Interfacing and implicit conjugate heat transfer module have been developed and validated

• A realizable v2-f turbulence model was implemented

• Loading distributions were found to be in good agreement with experiments

• Good agreement with experimental measurements was also found in terms of wall temperature

20/21

L. Mangani

MaschinentechnikCC Fluidmechanik und Hydromaschinen

Hochschule LuzernTechnik& Architektur

Technikumstrasse 21, CH-6048 HorwT +41 41 349 33 11, F +41 41 349 39 60

e-mail: [email protected]

Fifth OpenFOAM Workshop, June 21-24 2010, Gothenburg, Sweden

CONJUGATE HEAT TRANSFER ANALYSIS OF

NASA C3X FILM COOLED VANE

conjugate heat transfer analysis of nasa c3x film cooled...

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