Performance investigation of hybrid Darrieus-Savonius wind turbine compared to straight-bladed Darrieus turbine by Three-dimensional numerical simulation

The purpose of this research is to investigate the performance of hybrid Darrieus-Savonius wind turbines to achieve a model with high starting torque and suitable performance range. Straight-Bladed Darrieus wind turbines have high-amplitude fluctuations in torque and, at some angles, this torque is not enough to start the turbine motion. The hybrid turbine is compared with two equivalent models of straight-bladed Darrieus wind turbines. The first model has equal available power and the second model has equal height with the hybrid turbine. 3D simulation is performed using CFD and solving Reynolds averaged Navier-Stokes equations with finite volume method, using turbulence model and rotating mesh for rotation of the turbine. According to the results, the hybrid turbine in the starting mode has 22.24% and 17.5% lower standard deviation and 69.8% and 56.9% higher average torque, respectively, compared to the first and second equivalent turbines. In operational mode, the hybrid turbine at the rotational speed of 30 RPM has 16.1% and 27.3% lower standard deviation and 19.1% and 1.03% higher average torque, respectively. Therefore, the hybrid turbine at the start of the motion, as well as at low rotational speeds, has higher average torque and less fluctuations compared to equivalent Darrieus turbines.