Experimental Investigations and CFD Simulations of the Blade Section Pitch Angle Effect on the Performance of a Horizontal-Axis Hydrokinetic Turbine

Three twisted blades of a 1 kW prototype hydrokinetic turbine were designed based on the Blade Element Momentum (BEM) theory with a tip speed ratio of 6.25; water velocity of 1.5 m/s; angle of attack and pitch angle of 5 and 0°, respectively; a power coefficient of 0.4382 and a drive train efficiency of 70%. S822 hydrofoil was used to generate the coordinates of the blade cross-section. Experimental investigations and Computational Fluid Dynamics (CFD) simulations were carried out to estimate the performance of the blade design and know the effect of the section pitch angle on the performance of a horizontal-axis hydrokinetic turbine. The obtained results showed that the increase in the section pitch angle enhanced the performance up to a certain value. Further increase in the section pitch angle resulted in a low performance and a reduction of the rotation velocity, which in turn requires a high gearing ratio of the transmission system.