Dynamic behavior of a wave power buoy with interior on-board linear generator

Abstract

Wave energy conversion is attractive from the viewpoint of the size of the renewable resource, but prototypes continue to suffer from high costs, leading to the idea of combining a wave energy conversion function with a conventional function of another ocean or coastal infrastructure to achieve cost-sharing between functions. Here, a wave power device in which a linear generator is installed inside a sealed floating horizontal circular cylindrical buoy is studied, which has dual functions of a wave power converter and a floating breakwater. A two-dimensional Navier Stokes numerical wave tank is used, together with a Volume of Fluid method to model the detail of the buoy-wave interaction. After model validation, the primary conversion efficiency of the device, and the wave transmission and reflection coefficients are explored. It is found that the maximum primary conversion efficiency is close to 25%. In resonant state, the amplitude of the translator's relative oscillation could be much larger than that of incident wave. When the incident wave frequency departs from the natural frequency of the linear generator, the energy conversion efficiency deteriorates rapidly. When wave energy conversion reaches maximum efficiency, the corresponding wave transmission coefficients are in the range of 0.7–0.75, and the corresponding wave reflection coefficients are in the range of 0.2–0.3.