Effect of Upstream Deflector Plate Position on the Performance of Savonius Rotors

Abstract

Abstract Global warming has resulted from the excessive use of fossil fuels that are being used to meet the increasing energy demand. The use of renewable sources of energy for power generation has become important now than ever to mitigate the effects of global warning. Wind energy is one such alternative. It is clean, non-emitting, sustainable and environmentally friendly. In the present work, the performance of a Savonius rotor for wind energy application is studied experimentally and numerically. Three different rotor configurations having blade arc angles of 65°, 110° and 148° were tested in a wind tunnel. The rotor with blade arc angle of 110° performed the best. The peak power outputs for the 65°, 110° and 148° configurations are 0.05 W, 0.15 W and 0.11 W respectively. The 110° rotor model was later used to study the effect of deflector plate on the rotor performance. The best deflector plate position is γ = 0.3 at an exposure ratio of 0.6. At this configuration, the power coefficient is 0.06 compared to 0.021 recorded for the 110° model without deflector plate. Finally, the flow characteristics are studied in detail using commercial computational fluid dynamics (CFD) code ANSYS-CFX. The presence of the deflector plate shielded the returning plate from the approaching flow, hence reducing the negative torque and directed the flow onto the advancing blade. The combination of these two improved the performance of the Savonius rotor.