Thesis
Determining aerodynamic properties of sports balls in situ
Washington State University
Master of Science (MS), Washington State University
2010
Handle:
https://hdl.handle.net/2376/105199
Abstract
Understanding the aerodynamic properties of the ball can lead to better predicting the path of a ball's flight. Two important factors in the ball's trajectory are the aerodynamic lift and drag. Lift and drag vary with the ball's geometry, roughness, and translational and rotational speed. A numerical 3-D model was developed in Gambit and analyzed in Fluent. Results were inconsistent with experimental findings and determined unsuccessful. Wind tunnels may have measurable differences with ball drag occurring in play. The following considers lift and drag measurements from a ball propelled through static air in a laboratory setting. Measurements of aerodynamic properties in situ were similar to those made in wind tunnels. Smooth spheres, for instance, had a 10% reduction in drag through a low Reynolds region, comparable to wind tunnel results. Drag was observed for eight different ball types. Drag depended on the ball speed, rotation, roughness, and orientation. A so-called drag crisis was observed in some magnitude for all balls. A pronounced drag crisis was observed on a smooth sphere, golf ball, and flat seamed baseballs and softballs. As stitch height increased, drag increased. Orientation and rotation of the ball reduced the drag crisis. Lift was measured on three types of baseballs. All three balls showed a similar bilinear increase in lift with increasing spin. Results here showed higher lift than previous work. Scatter in measured lift and drag was larger for stitched balls than smooth or dimpled balls. Lift and drag were shown to be sensitive to seam height and orientation (which is difficult to control experimentally). This observed sensitivity may explain the disparity in lift and drag data found in literature.
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Details
- Title
- Determining aerodynamic properties of sports balls in situ
- Creators
- Jeffrey Ryan Kensrud
- Contributors
- Lloyd V. Smith (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525114301842
- Language
- English
- Resource Type
- Thesis