Performance improvement of a Savonius turbine by using auxiliary blades

Renewable energy sources have proved their importance on a global scale as an optimum alternative for fossil fuels. Wind energy is one of the most promising sources of renewable energy due to its availability. Savonius turbine is considered one of the best vertical axis wind turbines for converting the kinetic energy from the wind into mechanical energy at low wind speeds. The current work investigates the enhancement in the performance of conventional Savonius turbines using two configurations of auxiliary blades that are employed to enhance flow characteristics in the overlap region. The performance of the Savonius turbine, fitted with auxiliary blades, is compared with a newly developed turbine where the gap ratio is studied. The numerical simulation is carried out by solving unsteady Reynolds Averaged Navier–Stokes equations (URANS) using ANSYS fluent package. SST k-ω turbulence model is used to resolve the flow characteristics through the turbine, and it is validated and verified using previous experimental and numerical works. The current investigation results proved that the best power coefficient of the Savonius turbine augmented with curved and straight auxiliary blades increased by 8.4% and 9%, respectively. For the newly developed turbine, the optimum power coefficient increased by 13.6%. [Display omitted] •Enhancing the performance of conventional Savonius turbine by using auxiliary blades.•Studying the gap ratio to improve the optimum power coefficient.•Savonius turbine with curved and straight auxiliary blades increased by 8.4% and 9%, respectively.•Maximum Cp for the optimum configuration is 1.136 compared to conventional design.