Tip leakage effect on wells turbine

To improve the performance of Wells turbine used in oscillating water column wave energy system, it is requires deep understanding of the energy transfer mechanism from fluid to the turbine. The turbine blades have 90° stagger angle and works on bidirectional flows. Computational study of flow through the turbine by solving Reynolds averaged Navier-Stokes equations was carried out using ANSYS CFX® v14.0 commercial code. The main objective of this paper was to study the effect of different tip gaps (0.5%, 1% and 3% of the chord length) and to represent the tip leakage flow physics. It was found that the turbine performance was highly dependent on the tip gap size. The leakage flow interacted with the main stream and changed the flow separation profile and the turbine efficiency.