Hydrodynamic performance analysis of tower wake vortex tidal current energy capture system with swing oscillating hydrofoil

Abstract

In order to effectively utilize the tidal current energy in offshore wind farms, a swing oscillating hydrofoil system for tidal current energy capture is proposed. The system is constructed with oscillating hydrofoils as tidal current energy capture device combined with offshore wind turbine underwater tower. Lattice Boltzmann method and large eddy simulation method were combined, and the hydrodynamic characteristics and energy collection efficiency of a NACA0015 airfoil with different motion parameters were numerically analyzed with or without the influence of tower wake. The influence of pitch amplitude, heave amplitude and chord length of the hydrofoil on the energy collection efficiency of the system is analyzed from the aspect of vortex structure in the moving process. The results show that the energy collection efficiency of the oscillating wing is significantly improved by the trailing vortex of the tower, and the vortex shedding behind the tower can reduced by the addition of the oscillating wing, consequently, the fatigue load caused by the flow around the cylindrical body can be reduced. The energy capture efficiency of the oscillating wing can reach a highest efficiently of 30.72% in the wake vortex region of the tower, which has obvious advantages compared with the traditional oscillating wing tidal current energy capture device, and provides an effective way to improve the overall energy utilization rate of offshore wind farms.