A simple 3D river/tidal turbine model for farm computation – Comparison with experiments

Abstract : A simple CFD modeling using force source terms in the momentum equation is implemented, with the aim of computing the performance of a Darrieus turbine in its exploitation area and simulating the wake created behind the turbine. It uses the RANS solution method to reproduce ambient turbulent flow conditions with relatively low computational costs. The force distribution used is three-dimensional and has been calculated prior to implementation using a single URANS simulation of the flow through the real geometry of the turbine. To take into account the velocity and turbulent conditions of the flow impacting the turbine, forces can be corrected by the total forces obtained experimentally on a reduced-scale model for different flow cases. The impact on the turbine of upstream turbulence generated by a grid is studied experimentally. The power coefficient, drag force and transverse component of the force on the turbine are studied, as well as the shape and extension of its wake using Particle Imaging Velocimetry. Simplified models with different levels of detail are compared to the experimental data. The results turn out to be in good agreement in the far-wake, with an underestimation of the flow deficit in the near-wake.