1 / 30

Wind Tunnel Experiments Investigating the Aerodynamics of Sports Balls

Wind Tunnel Experiments Investigating the Aerodynamics of Sports Balls. Team Members: Colin Jemmott Sheldon Logan Alexis Utvich Advisor: Prof. Jenn Rossmann. Overview. Motivation/Background Flow Visualization Calibration Pitot tube Hot wire anemometer

jacob
Télécharger la présentation

Wind Tunnel Experiments Investigating the Aerodynamics of Sports Balls

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wind Tunnel Experiments Investigating the Aerodynamics of Sports Balls Team Members: Colin Jemmott Sheldon Logan Alexis Utvich Advisor: Prof. Jenn Rossmann

  2. Overview • Motivation/Background • Flow Visualization • Calibration • Pitot tube • Hot wire anemometer • Wiffle ball instrumentation/experiments • Baseball instrumentation/experiments

  3. Motivation • Previous studies have not produced a complete understanding of the flowfield around a spinning baseball • A comprehensive Wiffle ball study has not been documented before

  4. Background • Reynolds Number: Re = ρVD/μ • Lift Coefficient: CL = 2FL/ρU2A • Drag Coefficient: CD = 2FD/ρU2A

  5. Flow Visualization

  6. Calibration: Velocity Profiles • Measurements were taken to characterize flow in the test section • Pitot tube measurements were conducted at heights of 1, 2, 4, 6, 8, 10, and 11 in. and fan settings of 10, 30, and 50 Hz • Velocity profiles were constructed from these measurements

  7. Calibration: Velocity Profiles

  8. Calibration: Hot-Wire Anemometer • Device that determines airflow speed by measuring the rate of cooling of a heated wire. • Measures velocity fluctuations. • Turbulence level within tunnel was found to vary.

  9. Hot Wire Anemometer: 0.3% Turbulence

  10. Hot Wire Anemometer: 0.5% Turbulence

  11. Hot Wire Anemometer: 6% Turbulence

  12. Hot Wire Anemometer: Variance in Velocity

  13. Stationary Ball Force Measurements • A nylon rod with strain gauges mounted on it was used to measure the lift and drag forces on stationary balls. • Two full bridges were placed on the nylon rod to measure both axial and bending effects.

  14. Schematic of Strain Gauge Device

  15. Schematic of DC Amplifier • Gain ≈ 3000

  16. Amplifying Circuit

  17. Orientation of Ball for Drag Measurements

  18. Drag Coefficient: Results • The Drag Coefficient of the Wiffle ball was found to decrease exponentially with respect to the Reynolds number.

  19. Lift Force • It was discovered that Wiffle ball would experience a lift force if the holes of the ball were not symmetrically distributed about the horizontal axis.

  20. Lift Force: Results • The magnitude of the lift force seemed to depend on the angle at which the ball was tilted.

  21. Lift Force: Results • One of the potential reasons these lift forces come about is due to the air flowing into the ball.

  22. Lift Force: Results • The lift force results in the deflection of the wake.

  23. Spinning Baseball Apparatus

  24. Mass 0.32 lb 145 g Diameter 2.86 in 7.26 cm Velocity 80 MPH 36 m/s Angular Velocity 1800 rpm 30 Hz Lift Force 0.18 lb 0.79 N Lift Coefficient 0.20 - Drag Force 0.37 lb 1.7 N Drag Coefficient 0.54 - Mathematical Breakdown of a Curveball

  25. Coefficient of Lift by Spin Parameter Comparison

  26. Conclusion • Turbulence levels in the wind tunnel are satisfactorily low. • Lift force on a Wiffle ball is dependent on its orientation. • Lift coefficient for a spinning baseball was found to have stronger dependence on Reynolds number than previously reported.

  27. Acknowledgements • Sam Abdelmuati • Mike Wheeler • Prof. Carl Baumgaertner • Profs Bright, Cha, and Duron • Prof. Joe King • Prof. Toby Rossmann • Prof. Jenn Rossmann

More Related