Effect of Savonius blade height on the performance of a hybrid Darrieus-Savonius wind turbine
A vertical hybrid turbine commonly consists of a Darrieus and Savonius rotor where the Savonius is inside Darrieus turbine. This paper describes the experimental study of hybrid Darrieus-Savonius wind turbines by variation in Savonius blade height. In this case, the effect of the blade height of the Savonius blade was studied experimentally in a subsonic wind tunnel. The effect of the height of a Savonius blade relative to that of Darrieus called blade height ratios δ was investigated to know the hybrid turbine performance. The performance is represented by power and torque coefficient. The result shows that the hybrid turbine with height ratio greater than unity δ = 1.4 gives the highest power CP = 0.20 and torque coefficient CT = 0.129. It is investigated that the torque and the power coefficient have a higher value than that of Darrieus turbine, in which the increase in power and torque coefficient are 48% and 29%, respectively. This hybrid wind turbine with a blade height ratio greater than unity can be considered as an important variable in the wind turbine construction.