Performance evaluation of a direct drive wave energy converter using CFD

This paper presents a numerical study of the savonius type direct drive turbine incorporated in the rear bottom of typical chamber geometry of an oscillating water column chamber (OWC) for wave energy conversion. The paper deals with a numerical modelling devoted to investigate the effect of wave on the performance and internal flow of the savonius turbine in the components of an oscillating water column (OWC) system used for the wave energy capture. In the present paper, the flow behaviour is modelled by using the commercial code ANSYS CFX. The numerical flow models have been elaborated and simulated independently with different inlet geometries of a water chamber. Constant periodic wave flow calculations were performed to investigate the flow distribution at the turbines inlet section, as well as the properties of the savonius type turbine. The flow is assumed to be two-dimensional (2D), viscous, turbulent and unsteady. The commercial CFD code is used with a solver of the coupled conservation equations of mass, momentum and energy, with an implicit time scheme. Turbulence is modelled with the k–e model. Simulation result shows that the water velocity, differential pressure, and the best efficiency vary considerably depending on the savonius rotor angle. The obtained results also indicate that the developed models are well suitable to analyze the water flows both in the chamber and around the savonius rotor.