311 PIVによるサボニウスロータ周りの流れの可視化 : 流れ場に及ぼすオーバーラップの影響(S42-2 流れの可視化実験解析(2),S42 流れの可視化実験解析)  [in Japanese] 311 PIV measurements of the flow around a Savomus rotor : Effects of overlap on the flow field  [in Japanese]

PIV (Particle Image Velocimetry) measurements have been performed on three Savonius rotors with different overlap ratios (OL) by using a water tunnel to investigate the effects of OL on the flow around the rotor. The test conditions of OL include 0, 0.2 and 0.5. In the static condition, the flow through the overlap from the convex side of advancing bucket to returning bucket has been observed at the rotation angle α=35deg. This flow contributes to increase the static torque. On the country, the flow through the overlap is very weak at α=165deg where the static torque is smallest. In the rotational condition, the vorticity, whose sense of rotation was the same as the rotor rotation, was observed just at the lee of rotational center and it shifted toward the rotational center when increasing the rotational speed.