Performance analysis of a single stage modified Savonius hydrokinetic turbine having twisted blades

Savonius hydrokinetic turbine is one of the prominent vertical axis turbines for tapping hydro potential available in flowing streams in rivers or canals. In spite of their simple design, Savonius turbines have the problem of poor performance. This study aims to enhance the performance of turbine through modification in the blade shape. Under the present study, geometrical parameters namely blade arc angle and blade shape factor are considered to modify the blade shape of Savonius hydrokinetic turbine. A commercial unsteady Reynolds-Averaged Navier-Stokes (URANS) solver in conjunction with realizable k-ε turbulence model has been used for numerical analysis. Using CFD analysis, blade arc angle and blade shape factor are optimized on the basis of coefficient of power. Fluid flow distributions found around the rotor has also been analyzed and discussed. Based on the present investigation, the maximum power coefficient value of 0.426 is obtained for blade arc angle of 150° and blade shape factor of 0.6 corresponding to TSR value of 0.9 at flow velocity of 2 m/s.