A Twin Unidirectional Impulse Turbine for Wave Energy Conversion: Effect of Rotor Blade Profile on the Performance

There is a twin unidirectional impulse turbine topology in an oscillating water column for wave energy conversion, which has two unidirectional impulse turbines. In this topology, an oscillating airflow is rectified by these turbines. Previous studies show that the mean efficiency of this topology is predicted to be lower than the efficiency of a unidirectional impulse turbine. Therefore, the rectification of this topology needs more improvement. The objective of this study is to investigate the effect of the rotor blade profile on the performance of twin unidirectional impulse turbine by a wind tunnel test and computational fluid dynamics (CFD). In this study, 2 types of the rotor blade profiles in two cases of setting angles of guide vanes has been examined. As a result, the peak efficiency of Type A with θ = 14° was the highest of all turbines tested in this study. Furthermore, the flow state around the rotor and the guide vane is discussed.