Effect of Radial and Axial Clearance on the Performance of a Specially Designed Savonius Vertical Axiswind Turbine

Abstract

Savonius wind turbine (SWT) has a simple construction and can produce electricity in any wind direction. Although Savonius wind rotor has many advantages, but it has a low power coefficient when compared with other horizontal and vertical axis wind rotors. In this paper; an experimental study is carried out to investigate the effect of geometrical parameters (radial and axial clearances) on the performance of SWT in terms of torque coefficient and power coefficient. For this reason, analysis is carried out to optimize and improve the operation of such turbines. Two buckets' Savonius rotor model was selected, designed and manufactured with a diameter of ٨0 cm and height of 80 cm; without having a shaft between the end plates. The designed model was fabricated and tested in a low speed wind tunnel under an open type test section.The results of the present study show that, a maximum power coefficient was obtained at a clearance (ea) = 0.14d in axial direction. the Cp/Cp.max value for clearance (ea) = 0.14d in axial direction is compared with other investigation and founded that The Cp/Cp.max value of the present SVWT is higher than the other investigation at different value of the tip speed ratio (λ).