Simulation of Fluid-Structure Interactions in Aeronautical Applications€¦ · ·...

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December 2003 3rd FENET Annual Industry Meeting Slide 1

Simulation of Fluid-Structure Interactions in Aeronautical Applications

Martin KuntzJorge Carregal FerreiraANSYS GermanyD-83624 OtterfingMartin.Kuntz@ansys.com

Outline

• Flow Analysis with CFX-5.6– Numerical scheme– Turbulence modeling– Applications

• Structural Analysis with ANSYS– Applications

• Fluid-Structure Interaction with ANSYS / CFX– Multiphysics – Applications

ANSYS Organisation

ANSYS, Inc.

FluidsMeshingMechanical

CoreTechnologies

CFXICEM-CFDANSYS

IntegrationPlatform ANSYS Workbench

BusinessUnits

CFX-5 Numerical Method

• Finite volume method for hybrid grids

• Conservative, vertex-based discretization• Implicitly coupling of equations• Rhie/Chow pressure-velocity coupling• Algebraic multigrid• Scalable parallelization• Second order space and time discretization• Suitable for whole range of Mach- and Reynolds

numbers

CFX-5 Turbulence Modelingk-ε model

SST model

k-ε model

SST model

• Variety of models– For different types of flow– With different

computational effort• Examples

– One-equation models (KE1E)

– Two-equation models (SST, k-eps)

– Reynolds stress models (LLR, SSG)

– DES / LES models

NACA 4412 Airfoil

Shear-Stress Transport Model

• Optimized model for flow with separation and adverse pressure gradients

• Zonal model– k-omega model near the wall– k-epsilon model in freestream

• Blending dependent on solution• Additional limiter for turbulent viscosity • Automatic blending between• Wall treatment

– Logarithmic law on coarse grids– Low-Re formulation on fine grids

Aerodynamic Applications

• DLR F6 Wing/Body/Nacelle/Pylon configuration– Particpation at AIAA drag prediction workshop 2003,

Orlando– Analysis of accuracy and performance of CFD codes – Participants

• Industry: Airbus, Boeing, CESNA• Research centers: NASA; DLR, ONERA, NAL, QinetiQ• Universities

• Two Configurations• Wing / body• Wing / body/

nacelle / pylon

DLR F6: Lift for Wing Body

• Wing / body Configuration– Medium grid– 5.8 million nodes– ICEM-Hexa

• Excellent agreement for complete range of incident

Angle of Attack [Deg]

DLR F6: Turbulence Model

NASA Codes CFX 5

CL increased by 0.015 when SST A1 changed from 0.31 to 0.33 (Reduced separation, comparable to S-A turbulence model)

⎥⎦

⎤⎢⎣

1* ;minF

ρωραµ

CL increased by 0.015 when SST A1 changed from 0.31 to 0.33 (Reduced separation, comparable to S-A turbulence model)

⎥⎦

⎤⎢⎣

1* ;minF

ρωραµ

DLR F6: Lift vs. Drag

• Design parameter drag• Good agreement with SST model• Constant deviation for Spalart-Almaras model

Drag CoefficientDrag Coefficient

Computational Performance

• Lift and Drag converged after 120 iterations

• Oscillations in residuals due to transient separation

• Computation time about 12h fort 6 M nodes on 16 processors

Structural Analysis

• Initial focus on analysis of solids– Structural

analysis, thermal analysis

• Expanding focus to other fields– Multiphysics

environment

Structural

Thermal

Electrostatic

Electrical

Magnetic

HFEMAG

Strategy: Multiphysics

HeatHeatTransferTransfer

SolidSolidMechanicsMechanics

MagnetismMagnetismFluidFluidMechanicsMechanics

ElectricityElectricity

ANSYS MultiPhysics

Fluid-Structure Interaction

• Simultaneous run of individual software – Using advanced and

validated features of participating codes

– Exchanging data at common boundaries or overlapping domains

• Simultaneous solution of multiple fields in single solver– Non-optimal software

for individual fields– Requirement for

common grid– Large problems

become computationally expensive

⇒ ANSYS / CFX code coupling

FSI Classification

Thermal

Structural

ElectromagneticsMultiphysics

One-way Two-way

Explicit ImplicitIterativeCoupling algorithm

VolumeSurfaceInteraction domain

Heat flux Heat source

Mom. source

Pressure Force

Temperature

Velocity

Displacement

Exchange variables

Files MPITransfer medium

Two-way Coupling

Coef. loop

FSITimeloop

Stagger loop

FSITimeloop

CFX-5solver

ANSYSsolver

Interaction Domain

• Surface coupling at 2D interface

• Volume coupling at 3D domain

Fluid Solid

StructureElectro-

magneticsFluid

Data Transfer

• Variables – Variables available in both fields

• Transformation– System of units, scaling

• Interpolation– Dissimilar meshes

• Data transfer media– Files, MpCCI

FSI Examples

• Gas turbine• Heart valve• Aerofoil flutter

FSI Application: Gas Turbine

• Gas turbine rotor: 113 blades• Interaction: Structural / thermal / fluid• CFX

– Fluid flow and CHT in blades• ANSYS

– Directly coupled elements – Thermal and structural analysis of blades

Turbine: CFD

Pressure

Streamlines

Temperature

Turbine: Thermal/Mechanical

Displacement

Equivalent stress (SEQV)

Temperature

St Jude Heart Valve

• Popular bi-leaflet design• Coupling CFX-5 and Dynamic Rigid Body

Module• Several re-meshing steps

St Jude Heart Valve

Static Result Animation

St Jude Validation

• Valve Angle against time

Wing Flutter

• AGARD 445.6 testcase• Experimental set-up

described in AGARD Report 765

• Wall-mounted semispanmodel, mahogany

• Wing aspect ratio: 1.6525, quarter-chord sweepback angle 45 deg.

Wing Flutter

• Test case : Mach number 0.901• CFD grid: 272.600 nodes, CSA grid: 960 nodes• Grid generation ICEM-HEXA

Summary

• Fluid Structure Interaction software for aerodynamic applications– Accurate prediction of flow field and global

parameters– High performance – Efficient coupling algorithms

• Future– Continuation of validation work– Improvement of usability

Simulation of Fluid-Structure Interactions in Aeronautical Applications€¦ · ·...

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