ON BASIC PERFORMANCE OF A NEW AND SIMPLE VERTICAL-AXIS WINDMILL

抄録

We conduct subsonic wind-tunnel experiments, in order to investigate the basic aerodynamic characteristics of an autorotating finite flat plate in uniform mainstream, which has a potential for new windmills and waterwheels with very simple structures in addition to new mixers/diffusers. The present study focuses on both the effects of an aspect ratio AR and a tip-speed ratio Ω* upon the tumbling of the flat plate with a low thickness-to-depth ratio λ=0.013-0.02. We carry out the measurements using a torquemeter together with the synchronised measurements of the plate’s attack angle αfor the analyses with phase-averaging technique. As a result, the torque coefficient CT tends to decreases with increasing Ω*, and CT tends to become large with increasing AR. Power coefficient CP shows that the present phenomenon is suitable for low-speed windmills and waterwheels.