Design, Construction and Experimental Evaluation of a 500 W Savonius Wind Turbine Under Variable Wind Conditions

Abstract: The growing demand for renewable energy has increased interest in decentralized wind energy conversion systems capable of operating under low-wind conditions. Among vertical-axis wind turbines (VAWTs), the Savonius rotor is well suited for such applications because of its simple construction, self-starting capability, and ability to accept wind from any direction. This study presents the design, fabrication, and experimental performance evaluation of a 500 W Savonius wind turbine under variable wind conditions. The 500 W designation refers to the rated capacity of the AC generator coupled to the turbine and not the electrical power output obtained during the laboratory experiments. The turbine was tested under controlled indoor wind conditions generated by a standing fan at wind speeds of 3.3, 3.9, and 4.6 m/s. The AC output of the generator was rectified to DC before measurement. Rotor speed, wind speed, and voltage were measured using a digital tachometer, digital anemometer, NI USB-6008 data acquisition system, and digital multimeter. The maximum measured rotor speed, output voltage, and electrical power were 184 rpm, 4.30 V, and 1.849 W, respectively, at the highest tested wind speed of 4.6 m/s. The tip-speed ratio ranged from 1.047 to 1.135, while the maximum power coefficient (Cₚ) of 0.0990 was obtained at 3.3 m/s, indicating relatively higher aerodynamic efficiency at lower wind speeds. The results demonstrate the feasibility of the fabricated Savonius wind turbine for laboratory-scale performance evaluation and small-scale electricity generation under controlled low-wind conditions. Future work should employ wind tunnel testing to accurately determine the turbine's cut-in wind speed and comprehensively characterize its aerodynamic and electrical performance across a wider range of wind speeds up to the turbine's rated operating limit.