Study on the performance of a new VAWT with overlapped side-by-side Savonius rotors

Abstract

A new vertical axis wind turbine (VAWT) with overlapped side-by-side Savonius rotors is designed and analyzed in this paper. The new VAWT consists of several Savonius rotors with the distance between adjacent rotor axes being smaller than the rotor diameter, and the rotation of the rotors is similar to meshing gears. Transient computational fluid dynamics (CFD) simulations are adopted to evaluate the aerodynamic performance of the VAWT. Comparisons between the new VAWT and a traditional Savonius rotor are performed to illustrate the differences in torque, power, pressure distributions, and flow structures. It is found that the optimal distance between the rotors is 0.7 times the rotor diameter. The VAWT with two rotors has a maximum coefficient of power of 0.323 for TSR = 0.8, which is 38.72% higher than the traditional Savonius rotor. Especially, the new VAWT has an amazing efficiency improvement of 46.95% at TSR = 0.4. Furtherly, simulations are carried out on VAWTs with different numbers of rotors. It is found that the VAWT with 4 rotors has the highest coefficients of power of 0.416 at TSR = 0.6 and is 100.55% higher at TSR = 0.4 than the traditional Savonius rotor.