OWC devices are widely known among researchers in ocean energy. It is well-known that the efficiency of the device is closely related to the efficiency of the Power-Take-Off (PTO) which is usually a turbine. Traditionally, self-rectifying turbines are the most widely considered for working in an OWC because unidirectional turbines require a system of valves to rectify the flow. However, another option recently proposed is the use of the “twin turbine” configuration. This paper focuses on the performance of the turbines used in this configuration.
A numerical model has been developed and validated with data from the bibliography. This model has been used to analyze the flow field of the turbine when working in both performance modes: direct and reverse. Flow angles and loss distribution have been analyzed and interesting conclusions can be extracted.
Once the flow field has been analyzed, changes in the turbine geometry are proposed in order to improve the efficiency of the whole system by increasing the blockage made by the turbine in reverse mode. These changes, focused on the solidity of the rotor and guide vanes, were implemented and new simulations were carried out. The results obtained are the core of this work.