Computational Methods for the Design and Prediction of Performance of Ducted Marine Turbines

The increasing demand for sustainable energy sources to mitigate climate change has grown interest in harnessing renewable energy from the oceans. Ocean current energy, characterized by its reliability and predictability, stands out as a promising solution for a sustainable future. In this study, a coupling model that combines the Reynolds-Averaged Navier-Stokes (RANS) method with a lifting line method with a fully aligned wake is presented and applied to the design of horizontal axis marine turbines, aiming to optimize power output efficiency in uniform flow by using various duct shapes. The RANS method is employed to simulate the flow around the duct, while the turbine blades are represented by a pressure distribution function based on the lifting line model. At the design phase, the turbine's power coefficient has been scrutinized to assess the influence of duct geometry on turbine performance. Subsequently, a comprehensive hydrodynamic analysis, using a boundary element method, applied on both the duct and the turbine, is conducted to validate the power coefficient and the loading distribution of the designed turbines. Our results show that significant gains in the power delivered by the turbine can be achieved by the presence of a properly designed duct.