LDV Measurements of a Flow Field around a Wind Turbine

Abstract

The instantaneous flow distributions around a propellor-type 0.8 m diameter, two-bladed rotor in a wind tunnel were measured using a 2-color 4-beam LDV system. The axial and tangential velocity components were measured at 110 points on the horizontal plane which includes the rotor axis. The axial and radial components were measured on a vertical plane. All axial, tanegential and radial components were composed form these data. Especially, we measured instantaneous velocity distributions on a rotor plane where due to the bashing rotor, the velocity could not be measured by using a conventional anemometer such as a hotwire anemometer or a pitot tube. On the plane, the measured data showed the axial velocity component increased gradually after a blade passed, and decreased suddenly with the next passing blade. The calculated results from a simplified vortex model showed that the sudden decrement with the passing blade was almost induced by the bound vortex on that blade.