Effect of flexible blades on the Savonius wind turbine performance

This investigation is carried out to improve the efficiency of Savonius vertical axis wind turbine. A self-expandable blade that changes its shape during turbine rotation is proposed. The expansion of the advancing blade increases the positive torque and the contraction of the returning blade decreases the negative torque, which improves dramatically the turbine performance. Using a transient numerical method, two-dimensional (2D) model is established using commercial code ANSYS-fluent18.0. The study investigated firstly the effect of expansion amplitude on the turbine performance. The numerical model was validated against experimental results. Results indicated that the torque coefficient was improved by about 6% for the lowest expansion amplitude and by about 112% for the highest expansion amplitude. At high tip speed ratio, it was found that when the amplitude of expansion exceed certain value, the turbine loses the ability of self-starting.