Analytical and computational fluid dynamics models of Wells turbines for oscillating water column systems

The article deals with the development of an analytical model and computational fluid dynamics models to evaluate the functioning of monoplane isolated Wells turbines. For the former modelling typology, a blade element momentum code relying on the actuator disc theory was applied, considering the rotor as a set of airfoils. For the latter modelling typology, a three-dimensional multi-block technique was implemented to create the computational domain with a fully mapped mesh composed of hexahedral elements. The employment of circumferential periodic boundary conditions allowed for the reduction of computational power and time. The models use RANS or u-RANS schemes with a multiple reference frame approach or the u-RANS formulation with a sliding mesh approach. The achieved results were compared with analytical and experimental literature data for validation. All the developed models showed good agreement. The analytical model is suitable for a fast prediction of the turbine operation on a wide set of configurations during the first design stages, while the CFD models are indicated for the further investigation of the selected configurations.