Impact of Blade Pitch Angle on the Turbine Performance of a Vertical Axis Current Turbine

Abstract

Marine current energy conversion with turbines is a growing field of interest owing to its high energy density and predictability. For wind energy, three-bladed horizontal-axis turbines are the most common because of their high power capture. Forces on blades are considerably higher in marine currents, presenting challenges to turbine design. Current research focuses on blade optimization and the selection of reliable transmission systems, and data from experiments conducted in natural environments are lacking. This paper focuses on a five-bladed vertical axis marine current turbine with a direct drive generator especially designed for low rotational speed and presents data from real-world experiments and 3D simulation models. The paper specifically investigates the influence of blade pitch angle on power capture. Experiments have been conducted at 1.42 m/s with a turbine in a river for blade pitch angles of 0° and +3° (the angle is defined as the leading edge of the blade rotating outward, perpendicular to, and opposite of the turbine axis). Two numerical 3D models, namely a vortex model and an actuator line model, have been used to simulate the turbine under the same conditions (1.42 m/s and 0°, +3°). The experimental and simulation results show that a 0° pitch angle gives a higher power capture power than a +3° pitch angle. In addition, simulation models were used to simulate the performance for an extended range at pitch angles of −3° to +3°, a fixed tip-speed ratio, and a step size of 1°. The simulations show that +1° gives the highest power coefficient and increases the average power capture by up to 0.6%. The performance of vertical axis marine current turbines can be improved by increasing the pitch angle to 1° in the positive direction. By contrast, a negative pitch angle can increase the average power capture of wind turbines.

RIGHTS & PERMISSIONS

Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature