Numerical study into horizontal tidal turbine wake velocity deficit: Quasi-steady state and transient approaches

Abstract

The results of a computational fluid dynamics (CFD) study of a three-bladed horizontal axis tidal turbine (HATT) using both quasi-steady and transient numerical approaches are presented. The wake from the turbine is studied numerically and compared to experimental results carried out by a French research group at IFREMER. All results provided incorporate the Reynolds Averaged Navier Stokes (RANS) Shear Stress Transport (SST) turbulence model. Simulations cover a range of tip speed ratios (TSR = 0.5–8) with a constant inflow velocity of 0.8 m/s. The resulting power and thrust coefficients, Cp and Ct, are compared to experimental results for validation purposes. The results show a good level of agreement with further discussions of differences addressed herein. In order to garner meaningful information on which numerical methods should be used for wake studies, two families of simulations are performed at TSR = 3.67, using either the frozen-rotor quasi-steady approach, or the fully transient one. For both approaches, near and far field wake propagation is investigated and discussed. Results from both series of simulations are compared to experimental ones.