Effect of blade skew, endplate and casing groove on the aerodynamic performance of Wells turbine for OWC: a review

Abstract

Abstract The geometry modification of a bidirectional flow Wells turbine used in a wave energy converter can assist in overcoming the mammoth stall triggered by tip leakage, secondary flow on the blade surface, corner vortex, passage vortex, tip scrubbing, tip trailing edge vortex, boundary layer formation on hub and casing, and combination of all the listed making it a complex 3D flow. As the flow varies almost sinusoidally in each wave cycle in the ocean, it is inevitable to get a turbine having a higher operating range and average power output. Skewing a blade reduces the radial flow on the blade suction surface. A casing groove and endplate reduce tip leakage flow. These modifications give a significant improvement in the turbine performance. There are several design alternatives reported in the articles, and they have shown different results. In this article, the modifications and their effects are discussed in detail and concluded for future recommendations.