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Zerguy Maazouddin California State University Sacramento ME 143 – Vehicle Design

Computer Simulation of Vehicle Aerodynamic Forces and Moments Using Fluent 6.2 MSC VisualNastran 4D WorkingModel 2D. Zerguy Maazouddin California State University Sacramento ME 143 – Vehicle Design Professor Jose J. Granda Fall 2006. Introduction.

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Zerguy Maazouddin California State University Sacramento ME 143 – Vehicle Design

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  1. Computer Simulation of Vehicle Aerodynamic Forces and Moments UsingFluent 6.2 MSC VisualNastran 4DWorkingModel 2D Zerguy Maazouddin California State University Sacramento ME 143 – Vehicle Design Professor Jose J. Granda Fall 2006

  2. Introduction • Introduction to Fluent 6.2 and Gambit 2.2 • Ahmed Vehicle Model • Aerodynamic Influence of the Rear End Inclination Angle and Rear End Shape • 1989 Ford Escort • Wind Tunnel Test Simulation • Compare the Wind Tunnel Test Results to: • Ahmed Vehicle Model • ME 143 Course Text: Theory of Ground Vehicle 3rd Edition, J.Y. Wong • MSC VisualNastran4d Simulation • Escort’s Dynamics when the Front Lift Force > Rear Lift Force • WorkingModel 2D Simulation • Escort’s Dynamics when the Front Lift Force > Rear Lift Force

  3. Fluent 6.2 / Gambit 2.2 • Fluent 6.2 and Gambit 2.2 Are Used to Create Computational Fluid Dynamics (CFD) Simulations • ME 296 – Course on Fluent and Gambit • Fluent and Gambit located in RVR 4001 • Tutorials Available • Gambit 2.2 • Create the Model’s Geometry • Create the Model’s Mesh • Set Boundary Conditions • Export Your Gambit File to Fluent for CFD Simulation • You Are Able to Import Geometry from SolidWorks, ProEngineer, and AutoCAD • Fluent 6.2 • Define Model’s Solver, Energy Equation, Laminar / Turbulent Flow • Set the Material’s Physical Valve – Fluid or Solid • Define the Boundary Conditions • Run Simulation • Mathematical Equations, Assumptions, Physical Parameters, etc… can be found in the Fluent Documentation located in RVR 4001

  4. Fluent 6.2 Examples Fluid Flow Over a Military Aircraft Fluid Flow Over a Car Tire Space Aircraft Entry Into Mars Fluid Flow Over an SUV

  5. Ahmed Vehicle Model • Ahmed Vehicle Model Was Used to Study Vehicle Aerodynamics • Experimental Wind Tunnel Test • CFD Simulation Wind Tunnel Test • Aerodynamic Influence of the Rear End Inclination Angle and Rear End Shape Was Studied

  6. Ahmed Vehicle Model - Rear End Inclination AngleResults Show That as The Angle Increases The Aerodynamic Drag IncreasesF. Chometon1 20 deg 30 deg 12 deg 12 deg 20 deg 30 deg

  7. Ahmed Vehicle Model - Rear End ShapeResults Show That Adding a Rear End Deck, Spoiler, and New End Spoiler The Aerodynamic Drag Decreases. It Should Be Noted That In Some Cases Adding A Spoiler Will Cause The Front Drag Lift Force to Become Greater Than The Rear Drag Lift Force; Causing The Vehicle To Rollover. H. Fukuda2 20 deg 20 deg 20 deg 20 deg 20 deg 20 deg

  8. Create 2D Model in Gambit Create the Model’s Geometry Create the Model’s Mesh Set Boundary Conditions Export the Gambit File to Fluent for CFD Simulation You Are Able to Import Geometry from SolidWorks, ProEngineer, and AutoCAD Setup Simulation in Fluent Define Solver, Energy Equation, Laminar / Turbulent Flow Set Material Values – Fluid / Solid Set Boundary Conditions Set Order of Equations Monitor Physical Parameters Run Simulation Results 1989 Ford EscortWind Tunnel Test Simulation SolidWorks Model

  9. 1989 Ford Escort – GambitGeometry  Vertices

  10. 1989 Ford Escort- GambitGeometry  Edges

  11. 1989 Ford Escort – GambitGeometry  Faces

  12. 1989 Ford Escort – GambitWind Tunnel  Same Procedure

  13. 1989 Ford Escort – GambitWind Tunnel  Subtract Flow Face From Escort Face

  14. 1989 Ford Escort – GambitMesh  Grading – Edit, Defaults, Edge, Flexible Grading, Set to 1

  15. 1989 Ford Escort – GambitMesh  Face, Tri, 0.08 Interval Size

  16. 1989 Ford Escort – GambitMesh  Face, Tri, 0.08 Interval Size

  17. 1989 Ford Escort – GambitSet Boundary Conditions – Flow Face

  18. 1989 Ford Escort – GambitSet Boundary Conditions – Escort Face Save File File  Export  Mesh

  19. 1989 Ford Escort – FluentFile  Read Mesh  Display  Grid

  20. 2D Steady State Viscous Model Turbulent : k-epsilon Re = 4 x 106 1989 Ford Escort – FluentSolver / Viscous Model

  21. 1989 Ford Escort – FluentMaterial – Fluid – Air / Operating Conditions • Pressure Constant = 0 • Temp = 20 C Re = Vel x Model Height / viscosity Vel = 60 m/s Model Height = 1.09 m

  22. 1989 Ford Escort – FluentBoundary Conditions  Fluid - Air

  23. 1989 Ford Escort – FluentBoundary Conditions  Vel Inlet / Pressure Outlet

  24. 1st Order Equations First Order Upwind Approx 300 Iterations till Convergence 2nd Order Equations Second Order Upwind Approx 800 Iterations till Convergence 1989 Ford Escort – FluentSolution Controls

  25. 1989 Ford Escort – FluentInitialize / Equation Monitors / Run Simulation

  26. 1989 Ford Escort – FluentResults - Monitors These Graphs Show That The Simulation’s Mathematical Equations Converged

  27. 1989 Ford Escort – FluentResults – Velocity Contour

  28. 1989 Ford Escort – FluentResults – Static Pressure

  29. 1989 Ford Escort – FluentResults – Influence of Spoiler

  30. 1989 Ford Escort-Fluent-Results-Influence of SpoilerResults Show That Adding a Spoiler Will Reduce The Aerodynamic Drag

  31. 1989 Ford Escort – FluentResults – Aerodynamics Forces and Moments

  32. 1989 Ford Escort – FluentResults – Coefficient of Drag, Front Lift, and Rear Lift. Also, Rolling Moment and Yawing Moment

  33. MSC VisualNastran 4D Front Drag Lift Simulation • VisualNastran4d Simulation • Front Drag Lift Simulation • Impulse Results Click On Image to Start Video

  34. MSC VisualNastran 4D Front Drag Lift Simulation Results: Fluent Calculated the Rear Drag Lift to be Approx 891N. Therefore, to Simulate the Vehicle’s Front From Lifting Off The Road The Front Drag Lift Needs to Be Greater Than 891N. VisualNastran 4D Calculated this Force to be 3x105 N. Click On Image to Start Video VisualNastran 4D Calculated That the Impulse Force Between the Escort’s Body and Road will Be a Maximum 200,000 (kg m)/s

  35. WorkingModel 2DFront Drag Lift Simulation • WorkingModel 2D Simulation • Front Drag Lift Simulation • Total Force Results • Total Force Approx = 7000N

  36. WorkingModel 2DFront Drag Lift Simulation WorkingModel 2D Calculated That the Total Force Between the Escort’s Body and Road will Be Approx 7000N

  37. References • 1. Chometon, F., Gillieron, P. “Modelling of Stationary Three-Dimensional Separated Air Flows around an Ahmed Reference Model”.Third International Workshop on Vortex Flows and Related Numerical Methods. Vol. 7, 1999, 173-182 • 2. Fukuda, H., Yanagimoto, K., China, H., “Improvement of vehicle aerodynamics by wake control”. Society of Automotive Engineers of Japan. Vol 16 (1995) 151-155 • 3. Franck, G., D’Elia, J., “CFD modeling of the flow around the Ahmed vehicle model” • http://www.cimec.org.ar • Gillespie, T Fundamentals of Vehicle Dynamics. Society of Automotive Engineers, Inc. 1992 • Wong, J.Y. Theory of Ground Vehicles 3rd Edition. John Wiley & Sons, Inc. 2001

  38. Conclusion • Design of Vehicles • Aerodynamics – Fluent • Design – SoildWorks • FEA – Patran • Dynamic Analysis – VisualNastran4d • In-depth Analysis – MSC Adams • Questions

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