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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

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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
Overview
  • Motivation/Background
  • Flow Visualization
  • Calibration
    • Pitot tube
    • Hot wire anemometer
  • Wiffle ball instrumentation/experiments
  • Baseball instrumentation/experiments
motivation
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
background
Background
  • Reynolds Number:

Re = ρVD/μ

  • Lift Coefficient:

CL = 2FL/ρU2A

  • Drag Coefficient:

CD = 2FD/ρU2A

calibration velocity profiles
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
calibration hot wire anemometer
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.
stationary ball force measurements
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.
drag coefficient results
Drag Coefficient: Results
  • The Drag Coefficient of the Wiffle ball was found to decrease exponentially with respect to the Reynolds number.
lift force
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.
lift force results
Lift Force: Results
  • The magnitude of the lift force seemed to depend on the angle at which the ball was tilted.
lift force results21
Lift Force: Results
  • One of the potential reasons these lift forces come about is due to the air flowing into the ball.
lift force results22
Lift Force: Results
  • The lift force results in the deflection of the wake.
mathematical breakdown of a curveball

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