Aerodynamic characteristics and PIV analyses concerning tennis balls

14th International Conference on Fluid Control, Measurements and Visualization

Nakajima, T.^1 ; Hiratsuka, M.^2 ; Ito, S.^2 ; Konno, A.^2

Graduate School of Kogakuin University, 1-24-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo

163-8677, Japan^1

Kogakuin University, 1-24-2 Nishi-shinjuku, Shinjuku-ku, Tokyo

163-8677, Japan^2

关键词: Aerodynamic characteristics;    Air leaks;    Lift coefficient;    Outer surface;    Tennis balls;    Wake flows;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/249/1/012021/pdf
DOI  :  10.1088/1757-899X/249/1/012021

来源: IOP

【 摘 要 】

The structure of the current tennis ball is covered with a uniform felt fabric on the outer surface made of hard rubber. As the ball continues to hit, the surface felt wears. Also, air leaks out through the structure inside. These factors cause a difference in the aerodynamic characteristics of new and used balls. In this research, the aerodynamic characteristics of the old and new tennis balls rotating were investigated and the PIV results of the flow around the ball due to the wear of the felt producing these characteristics were showed. For the four types of tennis balls tested, used balls showed higher in drag coefficient than new balls, and new balls tended to be higher than used ball in lift coefficient. It is believed that deformation due to deterioration of ball rubber brings about a change in drag coefficient, which causes a change in lift coefficient due to wear of the surface felt. In the new ball, felt fluff stands, which indicates that the wake flow is large and inclined diagonally backward compared to the used ball, and the air around the ball is found to be caught by the felt fluff.