The Role of Circular Cylinders in Improving the Performance of the Savonius Wind Turbine

The important role of circular cylinders in improving the Savonius wind turbine performance was demonstrated experimentally in this study. This was carried out by placing circular cylinders in 3 (three) configurations, namely configuration-A: circular cylinder is placed in front of the returning blade with a constant distance S/D = 1.4; configuration-B: a circular cylinder is placed beside the advancing blade at various distances Y/D = 1.27, 1.42, 1.61, 1.82 and 2.00, and configuration-C: is a combination of the two configurations. The Savonius wind turbine used in this study is made of PVC pipe, which is split into two with a diameter of D = 165.2 mm and a height of H = 294.4 mm equipped with a shaft having a diameter (b) = 19 mm. In this experiment, the turbine torque is measured using a rope break dynamometer to obtain the power coefficient (CoP) and moment coefficient (Cm) as a function of the tip speed ratio (TSR). For a wind speed operated at 5 m/s, the results show that for configuration- A, the presence of a circular cylinder effectively improves the turbine performance, where the CoP of the turbine increases by about 19% at a TSR of close to 0.6 relative to a conventional turbine. As for configuration B, not all Y/D distances can improve turbine performance, but only at Y/D = 1.42 and 1.61. The highest increase in CoP was obtained at a distance of Y/D = 1.61, with an increase of more than 25% at TSR = 0.69 compared to a conventional turbine. On configuration-C, the circular cylinder installed at Y/D = 1.61 and 1.82 caused the improvement of the turbine performance, where Y/D = 1.61 gave an increase in CoP of about 27.8% at TSR of about 0.63 relative to the conventional turbine..