HLPW2-sasanapuri
- 1. © 2011 ANSYS, Inc. July 18, 20131 ANSYS CFD Results for the AIAA 2nd High Lift Prediction Workshop Robin Steed Sr. Software Developer Waterloo, Canada Vijay Veera Technical Services Engineer Sheffield, UK Bala Sasanapuri Sr. Technology Specialist Pune, India
- 2. © 2011 ANSYS, Inc. July 18, 20132 • Team HP –Don Mize –Imran Aziz Ahmad Acknowledgements
- 3. © 2011 ANSYS, Inc. July 18, 20133 Agenda Executive Summary 2 minutes Key Insights Method 3 minutes CFD Solvers & Discretization Solution Strategy Turbulence Modeling Results & Observations 12 minutes Grid Convergence Study Reynolds Number Study Lessons learned Q&A 3 minutes
- 4. © 2011 ANSYS, Inc. July 18, 20134 Key Insights • Excellent prediction of trends and accurate force/moment predictions with hybrid meshes in CFX and hybrid/poly meshes in Fluent • Poly meshes improved the accuracy for Fluent • Poly meshes have shown speed up of 2 to 3 times compared to hybrid meshes • SST k-w model has shown reasonably good results for the low Re case – Missing fairings in the simulation geometry might have caused some discrepancy – Further tests will be done with fairings included and by using SST transition model
- 5. © 2011 ANSYS, Inc. July 18, 20135 • Mesh: – Unstructured, hex, tet, wedge, pyramid, poly elements – Cell centered control volume – Co-located c.v.’s for all equation types • Numerics: – Density Based and Pressure Based Solvers – Default 2nd order space and time discretization – Coupled algebraic multigrid linear solver (AMG) • Physics: – Wide range of physics supported – Advanced turbulence models – Eulerian & Lagrangian multiphase – Combustion, radiation,…. • Parallel: – Domain decomposition – MeTiS & other partitioners ANSYS CFD Solver – Fluent 14.5 Integration Point Cell Vertex Control Volume
- 6. © 2011 ANSYS, Inc. July 18, 20136 • Mesh: – Unstructured, hex, tet, wedge, pyramid elements – CVFEM: c.v.’s defined by element mesh dual (polyhedral volumes) – Co-located c.v.’s for all equation types • Numerics: – Default 2nd order space and time discretization – Implicit pressure based all speed method – Coupled algebraic multigrid linear solver (AMG) • Physics: – Wide range of physics supported – Advanced turbulence models – Advanced turbomachinery models – Eulerian & Lagrangian multiphase – Combustion, radiation,…. • Parallel: – Domain decomposition – MeTiS & other partitioners ANSYS CFD Solver – CFX 14.5 Integration Point Cell Vertex Control Volume
- 7. © 2011 ANSYS, Inc. July 18, 20137 • Pressure Based Coupled Solver • Pseudo Transient Solution method • SST k-w Turbulence Model • Second Order Discretization for all equations • Mean Aerodynamic Cord based time step Solution Strategy
- 8. © 2011 ANSYS, Inc. July 18, 20138 • Meshes considered – Grid B Coarse – Grid B Medium – Grid B Fine – And all the above converted to polyhedra (Fluent) Grid Convergence Study: Meshes
- 9. © 2011 ANSYS, Inc. July 18, 20139 Grid Convergence Study: Results CM CDCL
- 10. © 2011 ANSYS, Inc. July 18, 201310 Grid Convergence Study: Results CM CDCL CD
- 11. © 2011 ANSYS, Inc. July 18, 201311 Grid Convergence Study: Results CM CDCL
- 12. © 2011 ANSYS, Inc. July 18, 201312 • Satisfactory grid convergence achieved on Medium mesh – CFX was not run on fine mesh due to import issues • Overall correct trends are predicted – Moment coefficient proved most difficult – All predictions were off the track at higher AoAs • Polyhedral mesh conversion resulted in 2 to 3 times faster solution, with similar or improved accuracy – Only poly meshes are used for the Reynolds number study with Fluent Grid Convergence Study: Observations
- 13. © 2011 ANSYS, Inc. July 18, 201313 • Meshes considered – Grid B Medium – Grid B Medium converted to polyhedra (Fluent) • Note about the Geometry – Simulations were performed with the geometry without including the fairings – Experimental results (for low Re case) are available for the geometry that includes fairings – This difference in the configuration can lead to some discrepancy in the results Reynolds Number Study: Meshes
- 14. © 2011 ANSYS, Inc. July 18, 201314 Reynolds Number Study: Forces/Moments CM CL CD
- 15. © 2011 ANSYS, Inc. July 18, 201315 Reynolds Number Study: Forces/Moments CM CL CD
- 16. © 2011 ANSYS, Inc. July 18, 201316 CF: Grid B Fluent Poly 7⁰ 16⁰ 18.5⁰ 21⁰
- 17. © 2011 ANSYS, Inc. July 18, 201317 Grid B Fluent Poly Low Re 7⁰ 16⁰ 18.5⁰ 21⁰
- 18. © 2011 ANSYS, Inc. July 18, 201318 Fluent: CP Distribution at 16⁰ 15% Span 45% Span 75% Span 89% Span
- 19. © 2011 ANSYS, Inc. July 18, 201319 Fluent: CP Distribution at 18.5⁰ 15% Span 45% Span 75% Span 89% Span
- 20. © 2011 ANSYS, Inc. July 18, 201320 Fluent: CP Distribution at 21⁰ 15% Span 45% Span 75% Span 89% Span
- 21. © 2011 ANSYS, Inc. July 18, 201321 CF: Grid B CFX 7⁰ 16⁰ 18.5⁰ 21⁰
- 22. © 2011 ANSYS, Inc. July 18, 201322 CF: Grid B CFX 7⁰ 16⁰ 18.5⁰ 21⁰
- 23. © 2011 ANSYS, Inc. July 18, 201323 Grid B CFX Low Re 7⁰ 16⁰ 18.5⁰ 21⁰
- 24. © 2011 ANSYS, Inc. July 18, 201324 CFX: CP Distribution at 16⁰ 15% Span 45% Span 75% Span 89% Span
- 25. © 2011 ANSYS, Inc. July 18, 201325 CFX: CP Distribution at 18.5⁰ 15% Span 45% Span 75% Span 89% Span
- 26. © 2011 ANSYS, Inc. July 18, 201326 CFX: CP Distribution at 21⁰ 15% Span 45% Span 75% Span 89% Span
- 27. © 2011 ANSYS, Inc. July 18, 201327 • SST k-w model has performed well even for the low Re case • CP matched well at inboard stations • CP deviated more at outboard stations • CL, CD showed correct trends and stall prediction • CM predictions were off from the experimental data • Lack of fairings in the simulation geometry must have contributed to some of the discrepancies Reynolds number study: observations
- 28. © 2011 ANSYS, Inc. July 18, 201328 • The transition results were removed from this presentation as they require further investigation of inlet conditions and mesh resolution • The transition cases will be recomputed and the results will be made available later A note on Transition model results
- 29. © 2011 ANSYS, Inc. July 18, 201329 Summary • Excellent prediction of trends and accurate force/moment predictions with hybrid meshes in CFX and hybrid/poly meshes in Fluent • Poly meshes improved the accuracy for Fluent • Poly meshes have shown speed up of 2 to 3 times compared to hybrid meshes • SST k-w model has shown reasonably good results for the low Re case – Missing fairings in the simulation geometry might have caused some discrepancy – Further tests will be done with fairings included and by using SST transition model
- 30. © 2011 ANSYS, Inc. July 18, 201330 Q&A • ANSYS designs, develops, markets and globally supports a range of CAE simulation software • A suite of multi-purpose software technologies for – Fluid Dynamics – Structural Mechanics – Implicit – Explicit Dynamics – Electromagnetics – Multiphysics • Selection of specialised tools – Specialist thermal/flow for electronics Thermal Emag Fluid CAD Import Param- terization Meshing Workflow Post- processing Structural About ANSYS
- 31. © 2011 ANSYS, Inc. July 18, 201331 ANSYS continues to actively participate in leading industry consortia & workshops Only commercial simulation company on the organizing committee of the NASA led aeroelastic prediction workshop Only commercial simulation company part of the Boeing led CARE consortium focused on the in cabin environment – 1D to 3D tool coupling focus Continued participation in AIAA High Lift, Drag Prediction and Propulsion Aerodynamics Workshops