Investigating the effects of wind concentrator on power performance improvement of crossflow wind turbine

Abstract

Small wind turbines are efficient for solving power supply problems in remote off-grid regions. A crossflow wind turbine is a drag-based small vertical axis wind turbine, which is suitable for small-scale power generation in the built environment because of its low aerodynamic noise. However, the power performance of a crossflow wind turbine is generally lower than that of a Savonius wind turbine. Aiming at improving the performance of a crossflow wind turbine, this study develops a wind concentrator by adding two parallel plates with flanges, which is based on the “wind lens” concept, to an arc-shaped windshield, which is based on an existing concept of a flow deflection device for a crossflow wind turbine. The effects of adding two parallel plates with flanges to the windshield (i.e., the effects of the wind concentrator) on the performance of the crossflow wind turbine are quantified with wind tunnel experiments and analyzed based on the flow field characteristics obtained by computational fluid dynamics simulations. The experimental results show that the wind concentrator enhances the maximum power coefficient of the crossflow wind turbine by 108% from 0.12 (without wind concentrator/windshield) to 0.25 (with the wind concentrator), whereas the arc-shaped windshield improves it by 48% from 0.12 to 0.17 (with the windshield). The numerical simulations reveal that the main cause for the power performance enhancement is a downward deflection of the approaching flow to the upper part of the rotor because of a significant increase in the pressure level on the upwind side of the upper flange and an overall decrease in the pressure level in the wake of the wind concentrator. In conclusion, adding two parallel plates with flanges to an arc-shaped windshield is effective for significantly enhancing the power performance of a crossflow wind turbine.