Near-Wake Interaction of a Tidal Turbine with an Integrated Downstream Centrifugal Reverse Osmosis Module*

The utilization of renewable energy in desalination leads to the production of drinkable water in electricity-deprived remote communities and coastal urban areas impacted by natural disasters contaminating water wells. We investigate a novel concept where a centrifugal reverse osmosis (CRO) module is directly integrated to the tidal stream turbine without electrical energy conversion and external power input. In this study, the impact of the cylindrical CRO module placed downstream of a tidal turbine model on turbine performance and the wake hydrodynamics is evaluated using Large Eddy Simulations (LES). The LES adopting the k-equation subgrid-scale model is validated using 1:20 scale laboratory experiments for the case of a turbine without the CRO module. For the simulations that will be discussed, the cylinder diameter of the CRO module is maintained at half of the turbine diameter (D_t) and is located at axial distances of D_t/2, D_t, and 2D_t from the rotor plane. In the preliminary simulations with D_t/4 axial distance, the cylinder significantly obstructs the flow, interacts with blade root and hub vortices, and causes a shift in tip vortices to a larger diameter, collectively leading to a reduction in turbine performance. This study will pave the way for identifying the optimal location of a CRO with minimal penalty on turbine performance, while also providing valuable insights into the wake flow-structure interactions.