Efficiency improvement of a self-rectifying radial impulse turbine for wave energy conversion

This paper aims to improve the performances of a self-rectifying radial impulse turbine used in wave energy conversion. The turbine design involves blades of circular profiles. The Design of Experiments method has been implemented for the efficiency optimization. The objective function aims to maximize the average turbine efficiency between the inhalation and the exhalation modes. A 3D viscous flow modelling has been performed with the ANSYS Fluent code. Simulations allow the turbine efficiency computation accordingly to the changes in the turbine geometry. Influence of ten geometrical parameters has been considered in the optimization process. According to a confidence degree of 95%, it has been found that only four of them have significant influence on the turbine efficiency. The rotor geometry admits the highest influence, particularly the blade angle. Additional analysis has been conducted by considering the rotor blade stagger angle. It has been found that the efficiency can be kept high in the both modes with a stagger angle of 4 degrees. Efficiencies more than 50% have been reached. The present turbine efficiency has been compared to that of a turbine of elliptical profiles. An increase of about 19% in the efficiency has been reached with the present turbine. (C) 2019 Elsevier Ltd. All rights reserved.