VELOCITY DISTRIBUTION OF LOW VELOCITY WIND TURBINE WITH WINGLET

Abstract

Drag induced by three dimensional flows in a wind turbine blade will increase the losses, which mean reduce the power generated by wind turbines. In airplanes winglet can decrease induced drag by reducing span wise flow. Theoretically bent the tip of wind turbine blade will give the same impact. The goal of this research is to investigate the velocity distribution of low velocity wind turbine with winglet. Research was conducted in an open loop wind tunnel while axial, tangential and radial velocity were measured using a five hole probe. The measurements were done in horizontal axis from -1.4R to 1.4R with a spacing of 0.2R. There were four variation in Z axis downstream of the rotor, i.e. Z/D=0.125, 0.25, 0.5, and 1.0. The pressures measured by the probe were then converted into axial, radial and tangential velocities. Results showed that flow downstream of the wind turbine is dominated by axial velocity and there were relative small tangential velocities so it might be ignored. The smallest axial velocity happened at the rotor axis, the velocity increase as the distance increase and almost equal to free stream velocity at -1.4 and 1.4R. There were a sudden velocity reduction in -1R and 1R. This reduction probably because the probe hits the vortex. Keyword :” five hole probe”, “ winglet”, “velocity distribution”