Analysis of an optimized radial impulse turbine for an OWC wave energy converter

Abstract

Abstract OWC concept is one of the most spread technologies among wave energy converters due to several reasons. However, this technology has always deal with the problem of the inherent bidirectional flow. Many solutions have been adopted such as a flow rectification system combined with a unidirectional turbine, several types of bidirectional turbines such as Wells turbine or impulse turbine. In this work, it is shown the performance of an optimized geometry for a radial impulse turbine, which improvement is based on the re-designing of the blades and settling angles of the vanes. A CFD model, validated against results from the bibliography, has been used to simulate both a new and a previous geometry taken as reference. The results of both turbines have been analysed in terms of the loss coefficients for each element in order to analyse the advantages of the new geometry. It has been found that the new geometry exceeds the efficiency of the previous geometry by 5%, being this gain based on the fact that sacrificing the rotor’s efficiency could lead to a great improvement in the performance of the guide vanes, reducing their loss and, in turn, lifting the turbine’s efficiency despite reducing the rotor’s one.