Power coefficient measurements of a novel vertical axis wind turbine

Wind tunnel experiments were performed to evaluate the power coefficients of three vertical axis wind turbines (VAWTs), namely, (a) conventional VAWT (two-bladed troposkien shape), (b) novel 50% shifted troposkien shape-vertical axis wind turbine (50% STS-VAWT), and (c) novel 100% STS-VAWT. All turbines had the same height, swept area, and NACA0015 airfoil with the same chord length. During the power coefficient measurements for each one of the turbines, the wind tunnel velocity was varied while the turbine rotation was kept constant through rheostatic load adjustment. Two different turbine rotations were used (600 rpm and 700 rpm). The resulting tip speed ratios (TSRs) ranged from approximately 2 to 6 in the current investigation. Both the power coefficients and the tip speed ratios were corrected against wind tunnel blockage effects. The 50% STS-VAWT model showed an overall better aerodynamic performance (both corrected and uncorrected power coefficients) when compared against the other two configurations, likely due to a combination of (a) power generation increased due to blade-wake interaction (BWI) reductions and (b) power generation capacity related to the blade length of each turbine.