Numerical investigation of the dynamic response and power capture performance of a VLFS with a wave energy conversion unit

Abstract

This paper numerically investigates the dynamic response and power capture performance of a Very Large Floating Structure (VLFS) with a Wave Energy Conversion (WEC) unit. The VLFS is composed of two hinged modules of which the relative pitch motion induced by waves is converted into electricity by the WEC unit. The discrete-module-beam-bending based hydroelasticity method is used to establish the equations of motion for the VLFS. A theoretical model is derived for optimizing the power take-off damping of the WEC unit. Based on the numerical results, it is found that (i) placing hinge near the foreside of VLFS is a good option for both the reduction of hydroelastic response and the enhancement of power absorption; (ii) for medium and long waves a larger wave incidence angle corresponds to a larger vertical displacement, a smaller bending moment and a decreased power capture width ratio of the VLFS; and (iii) the decrease of structural bending stiffness brings an increase of vertical displacement and a reduction of bending moment while its effect on power absorption is insignificant except for a very large bending stiffness.