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).