Casing optimization of a Savonius wind turbine

In an attempt to enhance the performance of a Savonius Vertical Axis Wind Turbine (VAWT), case sizing optimization was performed utilizing Computational Fluid Dynamics (CFD) technique. A 2D parametric optimization process was employed to optimize a number of assigned design parameters of the casing’s geometry. The configuration of El-Askary et al. (2015) was adopted as a starting baseline for the optimization. The turbine with the optimized casing provided a superior performance compared to a caseless one, specifically at low Tip Speed Ratios (TSRs). A maximum increase of 42.5% in the power coefficient (Cp) was attained at a tip speed ratio of 0.59. The obtained results demonstrate the nonexistence of a universal optimal casing shape that maintains peak turbine performance at all tip speed ratios. However, optimized casing dimensions follow a clear trend that is closely related to TSR values.