Adaptation Workshop > 21.06.2006 Folie 1 > TAU Adaptation on EC145 > Britta Schöning TAU Adaptation...

Folie 1 > TAU Adaptation on EC145 > Britta Schöning

Adaptation Workshop > 21.06.2006

TAU Adaptation for EC145 Helicopter Fuselage

Britta Schöning DLR – Inst. für Aerodynamik und Strömungstechnik

Alessandro D‘Alascio EUROCOPTER DEUTSCHLAND GmbH



Introduction

Geometries EC145 and BK117-C2

Grid generation

Calculation parameters

CFD results

Forces and moments (FLOWer/TAU/Experiment)

Pressure and skin friction lines (FLOWer/TAU)

TAU adaptation

Conclusion

Overview



IntroductionBackground and Objective

Unsteady RANS equations have reached a high degree of accuracy for moderate detached flows (like on airplanes).

Objective of the work was

to investigate the effect of turbulence models in high separation areas on particularly complex helicopter fuselage such as the EC145

investigation of TAU adaptation capability

comparison FLOWer / TAU

The blunt body of the EC145 helicopter is caused by its missions. Because of the high curvature in the area of the back door we can expect massive separations for which aerodynamic simulation tools are necessary.



CAD model CFD model

CATIA V4

Simplifying the geometry

Repairing the surface patches

Closing of air intakes and jet exhausts

GeometryCFD model: EC145 CAD model



stabilizers

back door area

EC145BK117-C2

conical junction air inlets - cabin roof

GeometriesComparison:EC145 (CFD model) BK117-C2 (experimental model)



88697 surface points25 prism layers (without chopping)3.7106 points pre-refined mesh

Grid Generation Hybrid Grid Generation by Centaur

TAU



Volume grid

C-O topology

64 blocks

80968 surface points

4.9 Mio. points

FLOWerGrid generationStructured Grid Generation by ICEM Hexa



M = 0.117

α = -18°, -12°, -6°, 0°, +6°, +12°

Re = 2.7·106

Multi-grid: 3v cycle

Steady calculation on Linux-Cluster (16 processors)

FLOWer TAU

Turbulence models

2-equation model

SST by Menter

7-equation model

RSM

2-equation model

Wilcox k-

2-equation model

SST by Menter

CFD Code DLR TAU/FLOWer Finite Volume Solver for 3D RANS Equations



0,00

0,10

0,20

0,30

0,40

0,50

-20 -15 -10 -5 0 5 10 15a (deg)

Cd

Drag coefficient

-0,40

-0,30

-0,20

-0,10

0,00

0,10

-20 -15 -10 -5 0 5 10 15

Cl

-0,70-0,60-0,50-0,40-0,30-0,20-0,100,000,100,200,30

-20 -15 -10 -5 0 5 10 15a (deg)

CM

Lift coefficient

Pitching moment

CFD resultsForces and Moments

0,00

0,10

0,20

0,30

0,40

0,50

-20 -15 -10 -5 0 5 10 15

BK117 C2 Wind Tunnel TestFLOWer: Unsteady, 6-eq. RSM turb. mod.FLOWer: Unsteady, 2-eq. SST k-w turb. mod.TAU: Steady, 2-eq. Wilcox k-w turb. mod.TAU: Steady, 2-eq. SST k-w turb. mod.

BK117-C2 ExperimentFLOWer: RSMFLOWer: SST k-ωTAU: Wilcox k-ωTAU: SST k-ω

a [] a []

TAU: SST k-ω 2. adaptation

cL

cm

cD



CFD Results Skin Friction Lines

2-equation SST k- ω turbulence model

7-equation RSM turbulence model

FLOWer

2-equation SST k- ω turbulence model

2-equation Wilcox k- ω turbulence model

TAU



X-axis

Cp

Z-a

xis

0.2 0.4 0.6 0.8 1 1.2 1.4-1

-0.8

-0.6

-0.4

-0.2

0

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0.8

1

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X-axis

Cp

Z-a

xis

0.2 0.4 0.6 0.8 1 1.2 1.4-1

-0.8

-0.6

-0.4

-0.2

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0.8X-axis

Cp

Z-a

xis

0.2 0.4 0.6 0.8 1 1.2 1.4-1

-0.8

-0.6

-0.4

-0.2

0

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EC145 mid sectionFLOWer - SST k- modelFLOWer - RSM modelTAU - SST k- modelTAU - Wilcox k- model

X-axis

Cp

Z-a

xis

0.2 0.4 0.6 0.8 1 1.2 1.4-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

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0.8

1

0.1

0.2

0.3

0.4

0.5

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0.8CFD Results Pressure Coefficient

Cut plane y = 0 [mm]



FLOWer – RSM model

FLOWer – SST k-ω model

TAU – SST k-ω model

TAU – Wilcox k-ω model

CFD Results Total Pressure Losses

Cut plane y = 0

α = 0°



3.7106 points

Total Pressure Lossesα = 0°

4.9106 points

TAU without adaptation

CFD Results Prediction of Wake



TAU Adaptation (1)

Pre-refined mesh: sufficient to predict total forces and moments

Goal: TAU adaptation to improve local field phenomena and interaction with tail

Adaptation variable: Total pressure losses

Two adaptation steps

Number of points: start grid 3.7Mio points

grid of 1st adaptation 4.3Mio points (+16%)

grid of 2nd adaptation 5.1Mio points (+18%)

Additional parameters: - minimum edge length

- no cut out boxes

- 2nd adaptation with re- and de-refinement approach

Adaptation of the SST turbulence model results



TAU Adaptation (2)

Start grid

1. adaptation

2. adaptation



Calculation on initial grid

Calculation on1. adaptation

Calculation on2. adaptation

TAU Adaptation (3)Wake, total pressure losses, y = 0, α = 0°

border of pre-refinement



CFD Results Pressure Coefficient

Cut plane y = 0 [mm]



TAU Adaptation (4)Wake, total pressure losses, α = 0°

Calculation on initial grid

Calculation on 2. adaptation



The comparison of forces and moments between the solvers FLOWer and TAU and the experimental data show a good agreement without TAU adaptation but with a pre-refined grid.

TAU adaptation improves resolution of local flow phenomena, necessary to be compatible with structured meshes (FLOWer).

Future plans:

Further work planned in SHANEL to qualify adaptation capability forhelicopter applications (BVI, helicopter wakes).

Conclusion, Outlook

Adaptation Workshop > 21.06.2006 Folie 1 > TAU Adaptation on EC145 > Britta Schöning TAU Adaptation...

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Transcript of Adaptation Workshop > 21.06.2006 Folie 1 > TAU Adaptation on EC145 > Britta Schöning TAU Adaptation...