Numerical Analysis of the Overlap Ratio of a Combined Blade Savonius Wind Turbine

South Africa's utilization of non-conventional energy resources must be improved. Because of the intense wind speeds in such areas, wind energy is exclusively used in the country's coastal regions. Savonius VAWTs can run at low speeds, making them suited for use in South Africa's interior regions. However, the power conversion efficiency of the Savonius VAWTs could be better. As a result, they must be modified. Changes to the rotor configuration are expected to boost positive aerodynamic torque. This study used numerical and analytical approaches to investigate the effect of blade overlap on the power coefficient, static torque coefficient, and overlap ratio. The study also sought to investigate wind flow interactions. For performance evaluation, the combined blade configuration was used. To solve the uRANS governing equations for numerical analysis, the Spalart–Allmaras turbulence model was employed using ANSYS Fluent 2022 R2. This numerical approach helped determine the power coefficient and velocity ratio at different time steps. The mathematical definition of torque was employed in obtaining the static torque coefficient when the angle of attack was altered for the analytical analysis. The power coefficient-time graph revealed that at a 0.2 tip speed ratio, the power coefficient ranges between 0.06 and 0.1, with a maximum velocity ratio of 0.333. It was also discovered that the maximum static torque coefficient increases when the overlapping ratio of the blades increases.