抄録
It is said that there are some differences between wind tunnel test and flight test on the ball aero dynamics. The reason of the difference seems to come from an acceleration and deceleration or unsteady motion at the flight test. In order to confirm the differences, PIV measurements around a flying table tennis ball are conducted. The high speed camera which frame rate is 10,000, is used to capture the instantaneous motion around the flying ball. The imaging region is 210mm×210mm. A coordinate transformation to the ball fixed coordinate system well captured the wake motion of non-rotating and rotating ball. It is observed that at non-rotating condition, the averaged wake velocity field of the ball is symmetric. On the other hand at rotating condition, it is asymmetric. These observations quantitatively agree with the wind tunnel test.
