Experimental And Numerical Study On Hydrodynamic Performance Of Vertical-axis Tidal-current Turbine

The tidal-current turbine is an important hydrodynamic part in harnessing tidal-current energy. Performance of a turbine is critical for the utilization of this renewable energy. Vertical-axis tidal-current turbine is able to adjust the change of incoming flow direction without any yaw mechanism, and more attention is now paid on its performance and design.The instantaneous angle of attack on the blade plays a significant role on the hydrodynamic performance of a vertical-axis tidal-current turbine with straight blades. In general, turbines with variable angles of attack can improve its performance, however additional devices required increase structural complexity and maintenance cost of the equipment. Therefore adding a preset angle of attack is reasonable.This paper investigates the hydrodynamic performance of a vertical-axis tidal-current turbine both experimentally and numerically. This tested turbine’s solidity is0.1146and its blade profile is NACA0018. The incoming flow velocity ranges from1.0m/s to2.0m/s, and The preset angles of attack on the blade are-3°,0°,3°, and+5°. Experimental results show that with the increase of the preset angle of attack, the hydrodynamic performance of the turbine increased from15.3%to34.8%, respectively. The results of numerical simulations also demonstrated such performance improvement. In addition, the numerical results also show that the optimal preset angle of attack should be+7°for the turbine studied, beyond this value, the hydrodynamic performance of the.turbine decreases. Therefore, such result should be considered in the design of a similar vertical-axis tidal-current turbine.With the help of numerical simulations, we predicted the performance of ducted and scaled turbine. Results show that ducted turbine has a much higher performance, its maximum power output is580W which increased about38.1%relatively; Hydrodynamic performance of the scaled turbine mainly followed former characteristic curve and laboratory data still useful after its parameters constrained changed.