Investigation on the flow fields and power mechanism of a Savonius rotor. (Flow visualization by a smoke-wire method).

Abstract

Unsteady flow fields around a Savonius rotor and its power mechanism are studied by a flow visualization experiment for various rotor angles and tip-speed ratios. For small tip-speed ratios, the rotor receives a corotating torque mainly due to the difference of the drag on both the blades. As the tip-speed ratio increases, a Coanda-like flow pattern is formed on the convex side of an advancing blade, and the corotaing torque is expected by the induced lift, though the torque due to the difference of the drag decreases. The power performance of a Savonius rotor can be explained reasonably by the flow visualization results.