Effect of the variations of the gap flow guides geometry on the savonius wind turbine performance: 2D and 3D studies

The Savonius wind turbine has been identified to have low power and torque coefficients. Numerous blade shapes and modifications have been proposed to improve its performance. In the present study, double gap flow guides of different lengths of 25–100 mm were introduced at different angular positions of 45–90° in a 0.5 m diameter blade Savonius turbine. The unsteady Reynolds Averaged Navier Stokes equations and the turbulence equations corresponding to SST k−ω were solved using the commercial software ANSYS FLUENT. Simulations were conducted in 2D and validated with 3D simulations at key points. The extracted results of the coefficient of performance and torque were compared with the available experimental data for the purpose of validation. A maximum increase of 12.24% in the coefficient of performance was observed for model 75 (degree angle) - 75 (mm length) at a tip speed ratio 1. Despite the high performance of model 75-75, model 60–75 showed a higher average of coefficient of performance across the considered range of tip speed ratios. The advantage of gap flow guides was explained in light of streamline plots, velocity vector plots and pressure distribution curves.