Numerical investigation of the aerodynamic performance of a hybrid Darrieus-Savonius wind turbine

A numerical simulation study on the combination of a Darrieus and a Savonius wind turbine is conducted. Hybrid T-II, T-III, and T-IV turbines are suggested with the same Darrieus turbine T-I. In the T-II and T-III, the Savonius turbine is at the center of the Darrieus turbine, whereas in the T-IV, the Savonius turbine is above the Darrieus turbine. The T-III Savonius turbine has half the radius of that of the T-II turbine. Results reveal that variations of the power coefficients, Cp with the tip speed ratio, TSR for the hybrid turbines have different slopes. It is observed that Cp increases with increasing TSR for the T-II and T-IV and does not decrease for the range of TSRs considered, in contrast with the Cp behavior of the T-I. The proposed hybrid T-IV turbine has also a larger Cp than the T-I turbine at the highest TSR.