Experimental Investigation on the Influence of Overlap Ratio on Savonius Turbines Performance

The paper presents an experimental investigation regarding the influence of the overlap ratio of blades of Savonius wind turbine over its power coefficient and power. Four Savonius wind turbines were fabricated with the overlap ratio of blades of 0.15, 0.20, 0.25 and 0.30. The turbines were subjected to an airflow directed through an opened subsonic wind tunnel. With the obtained results were determined, for each rotor, the variation equations of the rotations per minute depending on wind speed. Afterward, the function type and model of power variation curves depending on wind speed were determined. Following tests, it can be concluded that for wind speeds less than 4 m/s is suitable to be used the Savonius turbine with the overlap ratio of 0.15, while for wind speed that exceeds 4 m/s or areas where the wind has a turbulent character, the Savonius turbine with the overlap ratio of 0.30 is recommended.