Comparison of Non-Overlap and Overlap Savonius Wind Turbines in the Physics Aspect Using Computational Fluid Dynamics Method

Abstract

Wind energy has good potential as a renewable energy source. Savonius-type wind turbines can provide power generation at a low cost with minimal environmental impact. Due to its low efficiency, researchers were focused on increasing it through many methods, such as applying twisted-bladed, optimizing the blade shape, and applying overlap. Most researchers have studied the effects of overlap on Savonius blades only in terms of performance improvements. This study evaluates the effect of overlap on the Savonius blade from a physics perspective using the Computational Fluid Dynamics method to get a new approach based on the improvement. The models are 2-bladed Savonius with non-overlap and 0.2 overlap. The main software used is Ansys Student 2023 R2. The turbulent model chosen is a realizable k- enhanced wall treatment. Then, pressure and velocity coupling were done using SIMPLE: 2nd order upwind, 1st order implicit. As a result, the overlap model has a higher reverse flow but lower pressure for all Tip Speed Ratio. Another finding shows that turbulent kinetic energy decreases with overlap. For the non-overlap model, the amount of turbulence is greater downstream, which causes vortices to form and lowers turbine performance. So, the effects of the overlap blade result in higher average Torque Coefficient than non-overlap.