Research on the Flows of Backspin Movement in Table Tennis

This study discuss the distribution of the flows when the forced convection impacted on the spin and the static in table tennis; the research method is using the thermal flow in the experiment which the thermal flow will reflect according to the imaging principle when it passes through the spin sphere; this can be used to simulate the flows of balls in static condition and backspin ball in high-speed and low-speed rotation; the air flow passes through the spin sphere and generates the ball pressure which forms the quality variation of the spheres in table tennis competition; the results showed that it has a lower drag force, low fluid momentum and lower rectilinear speed when the sphere is in static condition, low Reynolds number; on the contrary, it has a higher drag force and increasing rectilinear speed of flows when the Reynolds number is high. When the ball is in backspin condition, the flows are symmetrical presented, and then the flows are gradually distributed, asymmetrical presented and are upward. The higher the Reynolds number is, the smaller the wake region is due to that the forced convection effect increased; the smaller the Reynolds number is, the ball will have more significant spin kinetic energy increasing rate when the spin speeds up.