There is a growing necessity to increase the efficiency of wind turbines especially the vertical axis
type. One of the challenges is to enhance the performance of Savonius wind turbines. Several methods have been
used for improving the power extraction efficiency through making some modifications in the shape of blades.
There is an important raised question about the best shape of blades that will maximize the power coefficient of
the Savonius wind turbine. This paper tries to answer this question by introducing an optimization analysis using
the optimal control numerical approach. Results indicated that the most important part of the blade that
influences the turbine efficiency is close to the tip radius of the blades. The combined effect of making gradual
slope of the blade profile and directing the blade curvature to be slightly outward near the tip region was
impressive. The flow separation point was shifted. The pressure distribution on blades surfaces was improved
and thus, the torque was increased. The third proposed design achieves an increase of 71% in the value of the
power coefficient corresponding to a free stream wind speed of 6 m/s compared to the conventional semi-circle
design.