Optimization of the helical Savonius rotor through wind tunnel experiments

In this paper, the authors propose a novel vertical wind turbine named helical Bach rotor. This rotor combines the helical rotor and the Bach rotor. The Bach rotor had a high value of power coefficient Cp; but it had negative values of static torque coefficient. These negative values would prevent the rotor to start on their own at certain rotor angles. Similarly, the helical rotor had a lower value of the power coefficient than the Bach rotor but it could provide positive values of static torque coefficient. Therefore, the combination of these two rotors would produce a helical Bach rotor with a better performance. Hence, this study attempted a new design of the rotor made of resin and glass fiber and tested it in an open wind tunnel. Tests were conducted to evaluate the power coefficient, torque coefficient and static torque coefficient for each rotor. The experimental results indicate that the helical Bach rotor had the highest power coefficient and static torque coefficient compared to the helical rotor. The helical Bach rotor yielded 0.2 power coefficient whereas the helical rotor yielded 0.18 power coefficient.