Casing Treatment of a Wave Energy Extracting Turbine

Performance of wave energy extracting turbine used in oscillating water column wave energy system depends on the turbine blade tip leakage flow. Computational study of flow through the turbine by solving Reynolds averaged Navier-Stokes equations were carried out using ANSYS CFX (R) v14.5 commercial code. The main objective of this paper was to study the effect casing treatment and the vortex pattern change which leads to stall limit change. It was found that the turbine performance in terms of operating range enlargement is possible through the casing treatment. The leakage flow interacted with the main stream and changed the flow separation profile as well as the turbine efficiency. It was found that the pick efficiency is decreased and it is shifted toward the higher flow coefficient as groove depth is increased, while the stall margin becomes wider. (C) 2015 The Authors. Published by Elsevier B.V.