Final Presentation


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Final Presentation

  1. 1. NASCAR Aerodynamics BY: Mark Angeloni Brendon Keinath Todd Sifleet
  2. 2. Why Does it Matter? <ul><li>At high speed aerodynamic effects play an enormous role in car performance. </li></ul><ul><li>By taking advantage of the effects of lift racecars have been able increase their corning ability, which in turn decreases lap time. </li></ul><ul><li>Also by minimizing drag they can maximize the top speed of the car. </li></ul>Source: Race Car Aerodynamics, J. Katz, 1995
  3. 3. Model Testing in a Wind Tunnel <ul><li>We used a 1/12 scale model of a NASCAR, because full-scale prototype testing is more expensive and time consuming </li></ul><ul><li>By running the model in wind tunnel at different velocities we are able to model different actual car velocities, gathering relevant information concerning aerodynamics. </li></ul>Source: Union College
  4. 4. Model Testing <ul><li>Problems With Model Testing </li></ul><ul><ul><li>Not possible to match Reynolds Number </li></ul></ul><ul><ul><li>Wind Tunnel cannot reach necessary speeds </li></ul></ul><ul><ul><li>If it could, Mach number would be too large and we’d have to worry about compressibility </li></ul></ul><ul><li>Some ways to fix this problem are: </li></ul><ul><ul><li>A larger wind tunnel with larger models </li></ul></ul><ul><ul><li>A different testing fluid with a higher density </li></ul></ul><ul><ul><li>Pressurizing and/or adjusting the air temp in the wind tunnel </li></ul></ul><ul><ul><li>Or in our case running the wind tunnel at several velocities and extrapolating to determine useful information. </li></ul></ul>
  5. 5. The Experiments <ul><li>Week 1- Surface Pressure measurements </li></ul><ul><li>Week 2- Lift and Drag measurements </li></ul><ul><li>Week 3- Particle Image Velocimetry, CFD analysis </li></ul>
  6. 6. Surface Pressure Measurments <ul><li>We used a model outfitted with 17 pressure taps to take pressure measurements at different point. </li></ul><ul><li>We measured the pressure at 2 different velocities 31 mph, and 51.5 mph. </li></ul><ul><li>Using these pressures we calculated pressure coefficients at different points of the model. </li></ul><ul><li>Using C p we can calculate pressures at any given point on the actual NASCAR. </li></ul>
  7. 7. Results - Pressure
  8. 8. Coefficient of Pressure
  9. 9. Lift and Drag <ul><li>The model, was connected to a dynamometer that measured force in both the x and y direction, essentially lift and drag.  </li></ul><ul><li>This data was collected using a data acquisition system as well, and processed with a PC.   </li></ul><ul><li>Using these measurements it was possible to calculate lift and drag on the car, as well as lift and drag coefficients. </li></ul>Source: Brad Bruno
  10. 10. Results – Lift Shows the Coefficient of Lift compared to the Reynolds Number of the experiment
  11. 11. Results - Drag Displays the coefficient of drag on the car compared to the Reynolds Number of the Experiment.
  12. 12. Particle Image Velocimetry <ul><li>PIV uses the wind tunnel along with a double pulsed laser technique to measure instantaneous velocity and to map out the flow field. </li></ul><ul><li>This provides a visual representation of the flow along the vehicle, streamlines and a qualitative representation of the velocities. </li></ul>Source: Brad Bruno
  13. 13. Results - PIV Flood Contour of Ford NASCAR Streamline Contour of Ford NASCAR
  14. 14. Results - PIV Zoomed In view of back end of NASCAR Zoomed in view of front end of NASCAR
  15. 15. Computational Fluid Dynamics <ul><li>CFD is a mathematical approach to modeling the flow around a vehicle. It uses an advanced computer program to map the flow field. </li></ul><ul><li>Like PIV, CFD gives qualitative representation of the velocity and pressure around the vehicle. </li></ul>Source: Google Images
  16. 16. Results – CFD, Velocity CFD of velocity of flow over car
  17. 17. Results – CFD, Pressure CFD of velocity of flow over car CFD of pressure distribution as a result of flow over car
  18. 18. Results – CFD, C p CFD of pressure coefficient as a result of flow over the car
  19. 19. Racecar Progression <ul><li>Reduction in aerodynamic drag by streamlining the shape of the vehicle </li></ul><ul><li>Increase the down force, negative lift, to increase cornering speeds </li></ul><ul><li>Raw hp vs. streamlining </li></ul>
  20. 20. The Proof is in the PIV <ul><li>The General Lee has a box like shape which results in a larger Drag than a rounder shape </li></ul><ul><li>Cd: </li></ul><ul><li>Cube = 2.2 </li></ul><ul><li>Rounded Cube = 1.2 </li></ul><ul><li>Sphere = 0.3 </li></ul><ul><li>Triangle = 1.5 </li></ul>
  21. 21. Charger vs NASCAR
  22. 22. Drag on Charger vs. NASCAR
  23. 23. Spoiler Effect <ul><li>The addition of a spoiler on the car results in greater downward force (or negative lift) which results in better cornering </li></ul><ul><li>The addition of a spoiler also increases the amount of drag on the car </li></ul>Source:
  24. 24. With or Without Spoiler
  25. 25. Why Drivers Draft <ul><li>Behind the car is a low pressure/low velocity pocket which aids in the reduction of drag on the following car </li></ul><ul><li>This increases efficiency and speed for both cars </li></ul>
  26. 26. Drafting Courtesy of
  27. 27. What we learned <ul><li>The strides made in streamlining designs of cars aided in decreasing the drag force along a vehicle </li></ul><ul><li>Spoilers create a larger down force on the vehicle which helps in keeping the wheels in solid contact with the ground at high speeds and cornering </li></ul><ul><li>These concepts together help increase speeds and lap times which is the overall goal </li></ul>
  28. 28. Is the data gathered useful? <ul><li>At High Reynolds Numbers the Coefficient of Drag and the Coefficient of Lift level off </li></ul><ul><li>We are in the transition area </li></ul><ul><li>The trends of our data do not quite level off so we can approximate the actual coefficients but can’t exactly place them </li></ul>