Abstract
The wind turbines with a flanged-diffuser shroud -so called "wind-lens turbine"- are developed as one of high performance wind turbines by Ohya et al. In the paper, the wind turbine performances are presented for both steady and unsteady winds. As the results, the compact-type wind-lens turbine shows better performance than the only rotor one in sinusoidally oscillating velocity wind. In order to make clear the relationship between flow field and the turbine performance, the flow fields are investigated by PIV and CFD, so that the several important flow structures on the wind-lens turbine performances are found. In particular, it is newly realized that the blockage vortex periodically generates in downstream for the same wind oscillating frequency, and decreases the power coefficient. However, the blockage vortex is vanished from the time averaged results of PIV. Hence, the time series measurement and analysis are very important for the appropriate design of the wind turbine in the unsteady flow.
