Abstract
The authors, in order to investigate the basic characteristics of an autorotating plate in uniform mainstream, which has a potential for new windmills and waterwheels with very simple structures in addition to mixers/difrusers. The present study concerns subsonic wind-tunnel experiments, focusing on both the effects of an aspect ratio AR and a tip-speed ratio Ω^* upon the tumbling of a flat plate with a low depth-to-width ratio λ = 0.02 - 0.08. The authors carry out flow visualisations and measurements using a hot-wire anemometer and a torque meter together with the synchronised measurements of a plate's attack angle α for the analyses with a phase-averaging technique. As a results, there are two flow modes I and II. In addition, the authors reveal the basic features of each mode, on the basis of instantaneous velocity profiles at each α, flow visualisations, wake deviations, momentum deficits and torque. These give us more useful information for efficient renewable-energy resources.
