Numerical study of savonius wind turbines with standard and Bach-profile blade variations

Numerical analysis is performed on Savonius turbine rotor with the standard blades and Bach-profile blades. The standard configuration was taken as a half semi-circular cylinder with overlap. Savonius turbine with overlap blades is considered because it gives better performance compared to that without overlap. Meanwhile, the Bach-profile blades tested are varied with arc surface angles of 124° and 135°. The objective of the study is to compare the performance of the Savonius turbine with standard blades with overlap to that with Bach-profile blades, particularly at very low wind speed. Steady, two-dimensional numerical simulations were performed on Savonius rotor turbine. Reynolds-Averaged Navier Stokes solver was used to solve the computations, with the turbulence model of the transition k-kl-ω model. The simulations were run at constant freestream velocities of 4 m/s and 7 m/s, and at various rotor angle positions. Overall, the results show that the rotor with the Bach-profile blade with arc surface angle of 135° has the highest static torque coefficient compared to other profile blades, for both the velocities tested. The self-starting capabilities are approximately similar for all the blade type tested.