Comparison of Various Blade Profiles in a Two-Blade Conventional Savonius Wind Turbine

Savonius turbines are one of the old and cost-effective turbines which extract the wind energy by the drag force. Nowadays, they use in urban areas to generate electricity due to their simple structure, ease of maintenance, and acceptable power output under a low wind speed. However, their efficiency is low and the improvement of their performance is necessary to increase the total power output. This paper compares four various blade profiles in a two-blade conventional Savonius wind turbine. The ratios of blade diameter to the blade depth of s/d = 0.3, 0.5, 0.7, and 1 are tested under different free-wind speeds of 3, 5, and 7 m/s and tip speed ratios (TSRs) in the range from 0.2 to 1.2. It is found that the profile of blades in a Savonius rotor plays a considerable role in power characteristics. Also, regardless of blades profile and free-wind speed, the maximum power coefficient develops in TSR = 0.8. In addition, increasing the free-wind speed enhances the rotor performance of all cases under consideration. Finally, it is revealed that the rotor with s/d = 0.5 provides maximum power coefficients in all free-wind speeds and TSR values among the rotors under consideration, whereas the rotor with s/d = 1 is the worth cases.