Aerodynamic properties of a shuttlecock with spin at high Reynolds number

The badminton shuttlecock has the smallest ballistic coefficient and exhibits the largest in-flight deceleration of any airborne sporting implement. In the present study, measurements of aerodynamic forces are performed at high Reynolds numbers, and the effect of shuttlecock deformation on aerodynamic properties was also investigated. A shuttlecock skirt has an array of diverging stems, whose ends are at the convergent end of the skirt, joined together in an end-ring. Furthermore, the shuttlecock rotates about shuttlecock's major axis in actual flight, and the experiments are performed by the shuttlecocks with and without rotation (spin). The effect of the flow passing through the gap between slots (stiffeners) located at leg portion of the shuttlecock skirt on aerodynamic characteristics is also demonstrated by using no-gap shuttlecock model, which is completely covered with cellophane tape. The free rotation rate of a shuttlecock increases with increasing Reynolds number, and the drag coefficient gradually decreases over Re = 86000 for the shuttlecock with no rotation. On the other hand, the drag coefficient for the shuttlecock with rotation is almost constant over the whole range of Reynolds number in the present study because the deformation of shuttlecock skirt for the shuttlecock with rotation becomes smaller than that for the shuttlecock with no rotation. However, there is no significant difference in drag coefficient between the shuttlecocks with and without rotation in contrast to the difference in drag coefficient between the shuttlecocks with and without gap. The drag coefficient for the shuttlecock with no gap is significantly smaller than that for the ordinary shuttlecock (with gap). For an ordinary shuttlecock, the air flows through the gap in the shuttlecock skirt, and this flow is related to high aerodynamic drag.