Aerodynamic Performance of an Elliptical-Bladed Savonius Rotor Under the Influence of Number of Blades and Shaft

Abstract

In the past, various influencing parameters of the conventional semicircular-bladed Savonius rotor such as overlap ratio, aspect ratio, number of rotor blades have been optimized through numerical and experimental investigations to improve its performance. Furthermore, the rotor performance under the influence of various blade profiles, shaft, endplates, and augmentation techniques has also been studied. Recent rudimentary studies with an elliptical-bladed Savonius rotor have demonstrated its potential to harness the wind energy more efficiently; however, its influencing parameters have not been thoroughly studied and therefore they need to be optimized to arrive at a suitable design configuration. In view of this, the objective of the present investigation is to optimize the number of elliptical blades on the rotor and then to find the influence of shaft with the optimized number of blades on the rotor performance. For this, 2D unsteady simulation is carried out with different combinations of blades, and after having optimized the number of blades, the influence of shaft on the rotor performance is studied. The continuity, unsteady Reynolds-Averaged Navier-Stokes (RANS) equations, and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial FVM based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude, turbulence intensity and streamline patterns are obtained and analyzed to arrive at the intended objective. The numerical investigation demonstrates an improved flow characteristics and performance coefficients of the 2-elliptical-bladed profile without shaft.