Blade optimization design of Savonius hydraulic turbine based on radial basis function surrogate model and L-SHADE algorithm

Abstract

The blade is the component responsible for capturing energy in the Savonius hydraulic turbine, and a good blade shape can extract more energy from the flow field. The shape of the turbine blade is optimized in this paper. First, the blade shape is expressed parametrically using a third-order quasi-uniform B-spline curve controlled by two parametric variables. Then, some initial design schemes are obtained through the grid sampling method from the design space and the torque coefficients of all initial design schemes are calculated using computerized fluid dynamics (CFD). Following this, a radial basis function (RBF) surrogate model is established by using initial design schemes and their corresponding torque coefficients. Then, the RBF surrogate model is solved by applying the L-SHADE. Finally, the resulting best design scheme is validated and further analyzed using CFD. By comparing the performance of the turbine before and after optimization, it is found that the power coefficient of the turbine with the optimized blades is increased by 7.07% at the tip speed ratio of 1, and the power coefficients at other tip speed ratios are also increased. In addition, the optimized blade has higher peak torque coefficients and its length is shortened by 15.34%.