NUMERICAL AND EXPERIMENTAL STUDY ON THE EFFECT OF OVERLAP ON SAVONIUS WIND TURBINE

Abstract

Wind as a renewable energy source is not yet fully exploited despite the permanent availability of this source. Moreover, in countries where renewable energy regulations are still absent, large-scale applications are still not available. The only wind turbines implemented are small-scaled applications owed to individual contributions. In this context, the Savonius wind turbine seems to be the most suitable choice at this scale because of its relatively low noise level, ease of manufacturing and maintenance, and self-starting aspect even at low wind speeds. However, the major drawback of such a turbine is its relatively low efficiency. In this framework, this study aims at assessing the various design parameters (number of blades, height-to-diameter ratio, and overlap ratio) of a Savonius wind turbine in an attempt to increase its efficiency. This is realised via computational fluid dynamics simulations followed by experimental validation through wind tunnel testing. Results show that the optimum configuration consists of a two-blade S-rotor with around 18% overlap. Future improvements could include shielding the returning blade to increase the torque.