Performance of a novel axisymmetric wave-concentrator-integrated oscillating water column system

Abstract

Inspired by metamaterial concentrators for electromagnetic (EM) waves, water wave concentrators have recently been invented to achieve localised wave height amplification, offering a promising pathway for enhancing wave energy conversion efficiency. This study proposes the integration of an oscillating water column (OWC) wave energy converter (WEC) with an annular wave concentrator, achieving significant performance enhancement through an axisymmetric omni-directional design. A computational fluid dynamics (CFD) model is developed to evaluate the energy capture performance of the integrated system after being validated against experimental data. The effects of wave nonlinearity and baffle configuration on the hydrodynamic efficiency are subsequently investigated. The results demonstrate that integrating the wave concentrator significantly enhances the hydrodynamic efficiency, yielding a 77.3% increase in the maximum capture width ratio (CWR) compared with a standalone OWC. Notably, the efficiency is enhanced several times for long-period waves (2.8–3.8 s), owing to wave refraction and superposition within the concentrator that amplify the free surface oscillation inside the chamber to nearly twice the incident wave amplitude. Wave nonlinearity further enhances the energy conversion rate near the resonant frequency, yielding an additional 43.5% efficiency improvement as the wave height increases from 0.050 m to 0.100 m. Increasing the number of guiding baffles can enhance the hydrodynamic efficiency through effective flow channelling, although the efficiency gain gradually levels off at high baffle densities.

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ORCID for Tahsin Tezdogan: orcid.org/0000-0002-7032-3038

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