Optimal Performance of a Modified Three-Blade Savonius Turbine Using Frontal Guiding Plates

Wind energy is one of the most promising sources of renewable energy. It is pollution-free, available locally, and can help in reducing the dependency on fossil fuels. Although a considerable progress has already been achieved, the available technical design is not yet adequate to develop reliable wind energy converters for conditions corresponding to low wind speeds and urban areas. The Savonius turbine appears to be particularly promising for such conditions, but suffers from a poor efficiency. The present study considers an improved design in order to increase the output power and the static torque of the classical three-blade Savonius turbine, thus obtaining a higher efficiency and better self-starting capability. To achieve this objective three geometrical properties are optimized simultaneously: 1) the position of an obstacle shielding the returning blade; 2) the position of a deflector guiding the wind toward the advancing blade; and 3) the blade skeleton line. As a whole, fifteen free parameters are taken into account during the automatic optimization process, carried out by coupling an in-house library (OPAL) relying on Evolutionary Algorithms with an industrial flow simulation code (ANSYS-Fluent). The output power coefficient is the single target function and must be maximized. The relative performance improvement amounts to more than 50% at the design point compared with the classical configuration.