Optimization of Two and Three Rotor Savonius Wind Turbine

The present work investigates the performance of Savonius wind turbine using two or three rotors. The new turbine design was found to have higher power coefficient compared with single rotor design. The peak average power coefficient of the three rotors was computed to be 50% higher than that of the single rotor design. The torque coefficient was also higher than that of the single rotor turbine at high tip speed ratio. This improved performance is attributed to the favorable aerodynamic interaction between the rotors which accelerates the flow around the rotors and generates higher turning torque in the direction of rotation for each rotor. The optimized arrangement of rotors showed that the upstream rotor and one downstream rotor should have a similar direction of rotation while the second downstream rotor is rotating in opposite direction.