On the effect of slotted blades on Savonius wind generator performances by CFD analysis

In this paper a new bucket configuration for Savonius wind generator is proposed. With the aim to increase the effect of the overlap ratio RS on the wind turbine performances and to increase the amount of lift force able to produce torque and power, slotted blades are investigated by means of the Computational Fluid Dynamics analysis. The numerical analyses are performed by Comsol Multiphysics® and the results obtained for a Savonius wind turbine with overlap only are compared to numerical and experimental benchmarks. Parametric analyses are performed, for fixed overlap ratio, by varying the slot angle β and the results show that for low angle β the Savonius rotor exploits improved performance at low tip speed ratio λ, evidencing a better starting torque. This circumstance is confirmed by the static analyses performed on the slotted blades in order to investigate the starting characteristic of the proposed Savonius wing generator configuration.