CFD-based improvement of Savonius type hydrokinetic turbine using optimized barrier at the low-speed flows

A Savonius turbine is a vertical axis hydrokinetic turbine (VAHT) utilizes in low-speed channels and rivers. In comparison with the other hydrokinetic turbines, the Savonius turbine is simple in construction and installation, and involves less installation cost; however, these turbines have low torque and power coefficients in comparison with other hydrokinetic turbines. The idea of this paper is utilizing a simple barrier to deviate the fluid flow from the reversing bucket of the Savonius turbine to enhance its generated power. In order to investigate the most appropriate length of the barrier, numerical modeling has been performed by applying computational fluid dynamics (CFD). The continuity, Reynolds Averaged Navier-Stokes - RANS equations and the SST transition turbulence model are numerically solved. The validation of the numerical simulation is assessed based on the experimental data of Sandia laboratories, and the results indicated good agreement with experimental data. Thereupon, the model is utilized for optimizing the length of the barrier in various cases. The power coefficient of different cases is compared with the obstacle-less conventional Savonius turbine. The results of this analysis reveal that utilizing a barrier in its optimum length increases the maximum generated power by about 18 percent.