A Numerical Investigation to Study Effects of a Savonius Rotor’s Plate Shape on its Optimum Overlap Ratio

Present study is aimed to investigate the relationship between blade shape of Savonius rotor and its optimum overlap, an important parameter that can improve the rotor’s performance superbly. To set a relation between rotor’s shape and its overlap, a new parameter called “trailing angle” was introduced in this study and by a novel design method, several models were designed to represent a wide range of trailing angles. The investigation has been carried out by using Reynolds Stress Method (RSM) through ANSYS Fluent commercial software package. The application of the method was validated by comparing the results of a conventional model with experimental data acquired from one of the references. Results of this study have proved that optimum overlap ratio is associated with blades’ trailing angle and by increasing the trailing angle, optimum overlap would decrease. The results also demonstrate that by application of a proper overlap ratio, power coefficient of the rotor would increase by nearly 22 percent.