ラグビーボールの短軸まわりの自励回転運動

概要

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It has been observed that a rugby ball, which is set to be able to rotate freely around its short axis in a wind tunnel, starts to rotate automatically when air flows through the wind tunnel. The rotation speed increases to about 600 rpm at airspeed of 25m/s. The purpose of this paper is to clarify the mechanism of auto-rotation of a rugby ball. In order to examine this phenomenon, wind tunnel tests were carried out to measure rotation speeds and static aerodynamic forces, and oil flow test was used to visualize the flow on the surface of a rugby ball. The results of the experiment revealed that the seam lines on a rugby ball are a major factor in inducing the boundary layer transition, and the resulting asymmetrical flow pattern is attributable to the auto-rotation phenomenon. In addition, it is estimated that the distortion of the cross-section shape of rugby ball and another blow-off area on the separation flow region contribute to the complicated aerodynamic characteristics.
東海大学の論文