Torque and drag characteristics of a six bladed savonius rotor

The research work has been carried out to study the aerodynamic characteristic i.e., drag coefficient torque coefficient etc. of a vertical axis type six bladed Savonius rotor. At first drag and torque characteristics of the six bladed Savonius rotor are determined by measuring the pressure distribution over the convex and concave surfaces of each blade at different angle of rotation. The experiment has been carried out at a Reynolds number of 2×10⁵ in a uniform flow jet produced by an open circuit wind tunnel. The pressure measurements have been made at 13 tapping points on each two blades of the rotor. Pressure on the convex and concave surfaces have been measured for every 10° interval of rotor angle up to 360° angle of rotation. The data obtained experimentally has been presented in terms of non-dimensional coefficients. To calculate drag force and torque in non-dimensional form, computer based software has been used and the output has been subsequently plotted and analyzed. The effects of individual blade and also the combined effects of six blades on different aerodynamic characteristics are analyzed in this research work. A quasi-steady approach has been applied for the prediction of the dynamic performance of the rotor using the static drag and torque coefficients. Power coefficient versus tip speed ratio curve for six bladed Savonius rotor has been drawn. This method results in a reasonable agreement with the measured power coefficient.