Wave power extraction for an oscillating water column device consisting of a surging front and back lip-wall: An analytical study

Abstract Traditional oscillating water column (OWC) devices are mostly fixed with almost no components allowed to move. To complement the research of OWC consisting of moving components, the capability in extracting wave energy for a device with a surging front and back lip-wall restricted by different spring stiffness values is investigated. A theoretical model is developed based on potential flow theory and solved by the matched eigenfunction method, and the pros and cons between the proposed model and the traditional fixed model are compared. The influential factors, including the wall drafts and chamber breaths, are explored to study the effects on the interested hydrodynamic parameters. To make full use of the inclusion of surging motion of lip-walls, a progressive optimized process of spring stiffness is proposed to obtain a superior efficiency curve. The results show that a relatively larger lip-wall draft and wider chamber breadth is more beneficial for the improvement of absorption efficiency for the dual-surging-motion model but the peak efficiency remains unchanged. An appropriate combination of the employed two stiffness values can expand the high-efficiency frequency bandwidth, and the peak efficiency can be improved to a better extent in contrast to the traditional fixed device.