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Computer Simulation of Vehicle Aerodynamic Forces and Moments Using Fluent 6.2 MSC VisualNastran 4D WorkingModel 2D Zerguy Maazouddin California State.

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Presentation on theme: "Computer Simulation of Vehicle Aerodynamic Forces and Moments Using Fluent 6.2 MSC VisualNastran 4D WorkingModel 2D Zerguy Maazouddin California State."— Presentation transcript:

1 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

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 3 rd 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 Car Tire Fluid Flow Over a Military Aircraft Fluid Flow Over an SUV Space Aircraft Entry Into Mars

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 Angle Results Show That as The Angle Increases The Aerodynamic Drag Increases F. Chometon 1 12 deg 20 deg30 deg 12 deg20 deg30 deg

7 Ahmed Vehicle Model - Rear End Shape Results 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. Fukuda 2 20 deg

8 1989 Ford Escort Wind Tunnel Test Simulation 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 SolidWorks Model

9 1989 Ford Escort – Gambit Geometry  Vertices

10 1989 Ford Escort- Gambit Geometry  Edges

11 1989 Ford Escort – Gambit Geometry  Faces

12 1989 Ford Escort – Gambit Wind Tunnel  Same Procedure

13 1989 Ford Escort – Gambit Wind Tunnel  Subtract Flow Face From Escort Face

14 1989 Ford Escort – Gambit Mesh  Grading – Edit, Defaults, Edge, Flexible Grading, Set to 1

15 1989 Ford Escort – Gambit Mesh  Face, Tri, 0.08 Interval Size

16

17 1989 Ford Escort – Gambit Set Boundary Conditions – Flow Face

18 1989 Ford Escort – Gambit Set Boundary Conditions – Escort Face Save File File  Export  Mesh

19 1989 Ford Escort – Fluent File  Read Mesh  Display  Grid

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

21 1989 Ford Escort – Fluent Material – 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 – Fluent Boundary Conditions  Fluid - Air

23 1989 Ford Escort – Fluent Boundary Conditions  Vel Inlet / Pressure Outlet

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

25 1989 Ford Escort – Fluent Initialize / Equation Monitors / Run Simulation

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

27 1989 Ford Escort – Fluent Results – Velocity Contour

28 1989 Ford Escort – Fluent Results – Static Pressure

29 1989 Ford Escort – Fluent Results – Influence of Spoiler

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

31 1989 Ford Escort – Fluent Results – Aerodynamics Forces and Moments

32 1989 Ford Escort – Fluent Results – Coefficient of Drag, Front Lift, and Rear Lift. Also, Rolling Moment and Yawing Moment 2D Escort Model CDCD C LF C LR Rm (Nm)Ym (Nm) Original Shape Spoiler Shape Theory of Ground Vehicles 3 rd Edition, J.Y. Wong CDCD Table 3.1Page 214 Ford Escort 1.3 GL Total Body Drag0.28Table 3.2Page 222

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 3x10 5 N. VisualNastran 4D Calculated That the Impulse Force Between the Escort’s Body and Road will Be a Maximum 200,000 (kg m)/s Click On Image to Start Video

35 WorkingModel 2D Front Drag Lift Simulation WorkingModel 2D Simulation  Front Drag Lift Simulation  Total Force Results Total Force Approx = 7000N

36 WorkingModel 2D Front 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, Fukuda, H., Yanagimoto, K., China, H., “Improvement of vehicle aerodynamics by wake control”. Society of Automotive Engineers of Japan. Vol 16 (1995) Franck, G., D’Elia, J., “CFD modeling of the flow around the Ahmed vehicle model” 4.Gillespie, T Fundamentals of Vehicle Dynamics. Society of Automotive Engineers, Inc Wong, J.Y. Theory of Ground Vehicles 3 rd 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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