Analyzing overlap ratio effect on performance of a modified Savonius wind turbine

Abstract

Savonius wind turbines are attractive options due to their simple structure, low noise, appropriate torque, and independence from the wind direction. In this study, a new experimental test is designed to analyze SR3345 and SR5050 blade profiles and to understand their effects on the performance of Savonius wind turbines. The fabricated wind turbine is placed in an open circuit wind tunnel with a velocity of 6 m/s. The power and torque coefficients of the turbine are compared with the two profiles considered based on overlap ratios between 0 and 0.3. Despite its increased stability, the results confirm that the central shaft reduces the power coefficient of the turbine. For blade SR3345, the optimum performance occurs at tip speed ratios of less than one, while for blade SR5050, the reasonable performance occurs at higher tip speed ratios. Blades SR3345 and SR5050 achieve the highest power coefficients at overlap ratios of 0 and 0.18 when a central shaft is present.