Improving the performance of Savonius wind turbine by installation of a circular cylinder upstream of returning turbine blade

The effect of the installation of a circular cylinder upstream of the returning turbine blade on the performance of the Savonius wind turbine was studied experimentally. The experiments are carried out for Re = 99,000. The circular cylinder with a diameter relative to the blade diameter (d/D) = 0.54 was installed at a distance between the circular cylinder and the returning blade relative to the blade diameter (S/D) varied from 1.4 to 2.2. The experimental results indicate that changes in distance S/D may improve the turbine power coefficient, where the maximum power coefficient occurs at S/D = 1.4, which increases in the power coefficient around 12.2% at a tip-speed ratio of 0.65 relative to the conventional one. However, when the circular cylinder is placed away from the returning blade (S/D > 1.8), there is practically no change in the power coefficient. (C) 2020 The Authors. Published by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University.