Flow on blades of wells turbine for wave power generation

Wells turbine has the cascade whose stagger angle is 90°, namely the blades are perpendicular to the axial velocity. Good performance is required from 0° to 90° angle of attack because the turbine is operated in the oscillating airflow produced with wave energy. Furthermore, very interesting and complex flows are experimentally observed by the oil film method for large angles of attack where the performance is strongly influenced, especially, the self-starting. This paper tries to analyze the mechanism of these three-dimensional flows around the turbine with the flow visualization and the numerical analysis, focusing on the off-design condition.