Shape optimization of a Savonius wind rotor with different convex and concave sides

This paper introduces an optimization procedure of a modified Savonius rotor with different convex and concave sides to maximize the power efficiency. A series of transient computational fluid dynamics (CFD) simulations are performed to find the peak coefficients of power (C_p) of each blade geometry. Then, a global response surface model is created according to the Kriging Method, which defines the relationship between optimization objective C_p and the design parameters. A Particle Swarm Optimization (PSO) algorithm is applied to finding the optimal design based on the response surface model. The optimal C_p is 0.2580 and is 4.41% higher than the traditional design. Comprehensive comparisons of torque, power and flow structures between the optimal and the traditional designs are performed to illustrate the mechanism of how the blade shapes improve the rotor performance. It is find found that the optimal blade shape has stronger tip vortices and recovery flows, which contributes to an increase in the performance of the rotor.