Wave power absorption by an oscillating water column (OWC) device of annular cross-section in a combined wind-wave energy system

This paper deals with a new combined concept consisting of an oscillating water column (OWC) device and offshore wind turbine for the multi-purpose utilization renewable energy resources. The is supported by monopile foundation, attached OWC coaxial foundation. Within chamber, exterior shell foundation are connected four vertical stiffening plates. Correspondingly, whole chamber divided into equivalent fan-shaped sub-chambers. A higher-order boundary element method then adopted to model wave interaction system. Numerical models based on two different approaches, namely ‘Direct’ ‘Indirect’, both developed in this study. In addition, self-adaptive Gauss integration treat nearly singular that occurs when field source points very close each other. detailed numerical analysis conducted case integrated NREL 5 MW regular irregular sea states. results illustrate significant extraction efficiency attained remarkable piston-like fluid motion induced within sub-chamber, power absorption not restricted direction. air compressibility makes negative effect especially frequency less than resonance piston-mode chamber. forces can balance other at specific conditions, leading zero net force also using optimal parameter, production be important supplement system operational