Comparative investigation of Savonius and hybrid H-Savonius wind rotor - an energy and exergy analysis

Exergy analysis is a vital tool for wind power development apart from energy analysis. The present study is based on a comparative energy and exergy analysis of Savonius wind rotor and hybrid H-Savonius wind rotor based on the parameters- power coefficient, power output and exergy efficiency, by using an experimental approach. For this the performances of a two-bladed Savonius rotor, a three bladed Savonius rotor, and a hybrid two-bladed Savonius and three-bladed H-rotor (H-Savonius rotor) are analyzed at four different wind velocities (7.5, 8.5, 10.5 and 12.5 m/s). The results show that power coefficient for the two-bladed Savonius rotor is higher than the three-bladed Savonius rotor with a maximum power coefficient of 0.18 at 10m/s wind velocity. The two-bladed Savonius rotor is then attached with the H-rotor having unsymmetrical S818 airfoil blades for which the maximum power coefficient of the hybrid turbine is creased to 0.197. The exergy efficiency of the H-Savonius rotor is found higher than any other rotor, which is increased by 8.5% compared to the two-bladed Savonius rotor and which is also higher than published result. The novelty of the present study is that it analyses the work potential of some prominent vertical axis wind turbines under varying wind speed conditions.