Experimental and numerical investigation of a land-fixed breakwater-type wave energy converter: An OWC device and a porous plate

Abstract

To further promote the commercialization of oscillating water column (OWC) devices and expand their application to coastal protection, it is crucial to enhance their survivability as much as possible while improving the wave energy conversion efficiency. In the present study, the hydrodynamic performance of a land-fixed, breakwater-type wave energy converter combining an OWC device and a porous plate was investigated. A series of physical experiments and numerical simulations were conducted to systematically verify each other and select the proper porosity of the porous plate and the gap spacing. On this basis, the effects of wave nonlinearity on hydrodynamic efficiency and wave-induced forces were comprehensively evaluated. The results indicate that under high frequency wave conditions, the porous plate can significantly reduce horizontal forces on the front wall with limited efficiency reduction. This phenomenon is more pronounced under the strong wave nonlinearity. The maximum reduction in horizontal force can reach 52%. At low wave frequencies, the effect of the porous plate is limited as the horizontal forces on the front wall are similar to those without the porous plate. The energy conversion efficiency increases in low frequency wave conditions because the porous plate assists first-order wave energy to enter the chamber by reducing the transfer of wave energy to high-order waves. In addition, due to the dissipation of wave energy by the porous plate, the wave reflection coefficient decreases and the wave dissipation coefficient increases in all cases.