Unsteady-state numerical analysis of advanced Savonius wind turbine

Abstract

ABSTRACT In order to improve the performance coefficients of the classic Savonius rotor, a newly-designed blade was proposed and numerically analyzed via CFD tools. For this purpose, a comprehensive-validated numerical analysis was carried out to take into account all aerodynamic aspects of the new design. The blade geometry was optimized by determining the best overlap ratio (0.47) which led to the highest performance at different tip speed ratios. The better performance of the optimal advanced Savonius rotor compared to the classic rotor was demonstrated by comparing its torque and power coefficients at different tip speed ratios. It is shown that working at relatively low tip speed ratios results in higher torque coefficients with more superiority over the corresponding classical rotor; however, to achieve more stable and regular blade rotation with less noise and fluctuations, tip speed ratios around 0.75 and smaller are proposed. In order to demonstrate the separation points, the wake phenomenon, and vortices behind the rotating blades, the pressure, velocity, and vorticity contours were prepared and analyzed.