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, C-p with the tip speed ratio, TSR for the hybrid turbines have different slopes. It is observed that C-p 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 C-p behavior of the T-I. The proposed hybrid T-IV turbine has also a larger C-p than the T-I turbine at the highest TSR.