Power capture analysis of a five-unit oscillating water column array integrated into a breakwater in terms of flow field visualization

Abstract

Oceanic waves possess immense untapped potential as a renewable energy resource, presenting a remarkable opportunity for energy extraction. To unleash the full extent of wave power within a given region and generate substantial quantities of electricity for widespread distribution, it is plausible to envision the deployment of wave farms—expansive arrays comprising wave energy converters. This study investigates the performance of an oscillating water column (OWC) array system integrated into a straight breakwater for wave power extraction. The array consists of five identical rectangular-shaped OWC units with a circular-curve bottom profile, arranged in a linear configuration. Computational Fluid Dynamics simulations are conducted to analyze the power capture of the array system and understand the operational dynamics compared to individual OWC device. Flow field visualization is employed to gain insights into the array effects and the influence of the transverse spacing between the interior units. The array configuration reveals that the OWC units positioned at the lateral sides exhibit the highest performance, while the central chamber achieves the lowest performance. However, none of the units within the array surpass the wave power extraction of an individual OWC device. The array effect introduces interference, significantly influencing the velocity field distribution of the water flow and contributing to disparities in wave power extraction between the individual device and the closely-adjacent array configuration. The study also emphasizes the role of transverse spacing between the interior units in the array. Within a certain range of transverse spacing, increasing the spacing enhances the power capture by mitigating destructive interactions involved in the inflow and outflow processes between adjacent chambers. However, when the transverse spacing becomes sufficiently large, the behavior of each unit within the array resembles that of an individual OWC device, and the constructive interaction effects between units become negligible, thereby weakening wave power extraction.