Simulation of Fluid-Structure Interactions in Aeronautical Applications

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1 Simulation of Fluid-Structure Interactions in Aeronautical Applications Martin Kuntz Jorge Carregal Ferreira ANSYS Germany D Otterfing December rd FENET Annual Industry Meeting Slide 1

2 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 December rd FENET Annual Industry Meeting Slide 2

3 ANSYS Organisation ANSYS, Inc. Business Units Mechanical Meshing Fluids ANSYS ICEM-CFD CFX Core Technologies Integration Platform ANSYS Workbench December rd FENET Annual Industry Meeting Slide 3

4 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 December rd FENET Annual Industry Meeting Slide 4

5 CFX-5 Turbulence Modeling 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 k-ε model SST model December rd FENET Annual Industry Meeting Slide 5

6 NACA 4412 Airfoil December rd FENET Annual Industry Meeting Slide 6

7 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 December rd FENET Annual Industry Meeting Slide 7

8 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 December rd FENET Annual Industry Meeting Slide 8

9 DLR F6: Lift for Wing Body Wing / body Configuration Medium grid 5.8 million nodes ICEM-Hexa Excellent agreement for complete range of incident Lift Coefficient Angle of Attack [Deg] December rd FENET Annual Industry Meeting Slide 9

10 DLR F6: Turbulence Model NASA Codes CFX 5 C L increased by when SST A1 changed from 0.31 to 0.33 (Reduced separation, comparable to S-A turbulence model) * ρ k a 1 ρ k µ t = min α ; ω Ω F 2 December rd FENET Annual Industry Meeting Slide 10

11 DLR F6: Lift vs. Drag CFX-5 Lift Coefficient Drag Coefficient Drag Coefficient Design parameter drag Good agreement with SST model Constant deviation for Spalart-Almaras model December rd FENET Annual Industry Meeting Slide 11

12 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 December rd FENET Annual Industry Meeting Slide 12

13 Structural Analysis Initial focus on analysis of solids Magnetic Structural analysis, thermal analysis Electrostatic Fluid Expanding focus to other fields Multiphysics environment Electrical Structural HF EMAG Thermal December rd FENET Annual Industry Meeting Slide 13

14 Strategy: Multiphysics ANSYS MultiPhysics Heat Transfer Electricity Solid Mechanics Fluid Mechanics Magnetism December rd FENET Annual Industry Meeting Slide 14

15 Fluid-Structure Interaction Simultaneous solution of multiple fields in single solver Non-optimal software for individual fields Requirement for common grid Large problems become computationally expensive Simultaneous run of individual software Using advanced and validated features of participating codes Exchanging data at common boundaries or overlapping domains ANSYS / CFX code coupling December rd FENET Annual Industry Meeting Slide 15

16 FSI Classification Multiphysics CFD Electromagnetics Structural Thermal Coupling algorithm Iterative One-way Explicit Implicit Two-way Interaction domain Surface Volume Exchange variables Pressure Force Displacement Velocity Mom. source Heat flux Heat source Temperature Transfer medium Files MPI December rd FENET Annual Industry Meeting Slide 16

17 Two-way Coupling FSI Time loop FSI Time loop ANSYS CFX-5 Stagger loop solver solver Coef. loop December rd FENET Annual Industry Meeting Slide 17

18 Interaction Domain Surface coupling at 2D interface Volume coupling at 3D domain Fluid Fluid Structure Solid Electromagnetics December rd FENET Annual Industry Meeting Slide 18

19 Data Transfer Variables Variables available in both fields Transformation System of units, scaling Interpolation Dissimilar meshes Data transfer media Files, MpCCI December rd FENET Annual Industry Meeting Slide 19

20 FSI Examples Gas turbine Heart valve Aerofoil flutter December rd FENET Annual Industry Meeting Slide 20

21 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 December rd FENET Annual Industry Meeting Slide 21

22 Turbine: CFD Pressure Streamlines Temperature December rd FENET Annual Industry Meeting Slide 22

23 Turbine: Thermal/Mechanical Displacement Temperature Equivalent stress (SEQV) December rd FENET Annual Industry Meeting Slide 23

24 St Jude Heart Valve Popular bi-leaflet design Coupling CFX-5 and Dynamic Rigid Body Module Several re-meshing steps December rd FENET Annual Industry Meeting Slide 24

25 St Jude Heart Valve Static Result Animation December rd FENET Annual Industry Meeting Slide 25

26 St Jude Validation Valve Angle against time December rd FENET Annual Industry Meeting Slide 26

27 Wing Flutter AGARD testcase Experimental set-up described in AGARD Report 765 Wall-mounted semispan model, mahogany Wing aspect ratio: , quarter-chord sweepback angle 45 deg. December rd FENET Annual Industry Meeting Slide 27

28 Wing Flutter Test case : Mach number CFD grid: nodes, CSA grid: 960 nodes Grid generation ICEM-HEXA December rd FENET Annual Industry Meeting Slide 28

29 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 December rd FENET Annual Industry Meeting Slide 29