Numerical evolution of unsteady wake characteristics of H-type Darrieus Hydrokinetic Turbine for a hydro farm arrangement

Abstract

In this study, the CFD method is carried out in the wake region of an H-type Darrieus hydrokinetic turbine. The hydrodynamic investigation was examined with symmetric and non-symmetric foil shape to maximize output power coefficient and wake recovery. The SST (Shear Stress Transport) k-ω turbulence model was used on 2-D and 3-D unsteady numerical analyses. The obtained power coefficients from 2-D and 3-D analyses at different Tip Speed Ratios (TSR) were validated by comparing with the experimental data from the literature. As the experimental study, the maximum power coefficient was obtained at TSR=1.05 for a 3-D analysis of the NACA0018 foil configuration of the hydrokinetic turbine. It is found that the results of 2-D and 3-D calculated by the SST k-ω are in good agreement with the experimental data in terms of power coefficients curve trend at investigated TSR range between 0.9–1.4. The difference between the power coefficient results of 3-D and experimental data varies between 1.8-11% ranges. The performance and flow characteristics of the wake region were also compared in detail for different foil by CFD. Therefore, the SST k-ω model can be preferred as an acceptable model to analyze the performance and flow characteristics of hydrokinetic turbines.