Wave power extraction from a wave farm of tubular structure integrated oscillating water columns

Abstract

To efficiently utilize the abundant wave power in the ocean, it is necessary to deploy a wave farm. This paper considers a wave farm of oscillating water columns (OWCs) integrated into tubular structures. Each OWC device within the wave farm is constructed with a vertical tubular design, incorporating a partially open submerged side that faces the sea. At the top of each device, an air turbine is installed to harness the pneumatic power generated by incoming water waves. To assess the performance of the wave farm, an analytical model is developed using the eigenfunction matching method within the framework of linear potential flow theory. Subsequently, this model is utilized to assess the efficiency of two wave farm setups: a line array with varying numbers of devices and a square array consisting of four devices. When the openings of the OWC devices are deployed on the exterior side of the square array, the majority of the wave power captured by the wave farm is contributed by the windward OWC devices, over a wide range of wave conditions examined. However, when the openings are placed on the interior side of the square array, wave resonance among the OWC devices becomes a significant factor affecting the wave farm’s performance. In this case, the leeward devices could capture more wave power compared to the windward ones. Large wave excitation forces acting on the OWC devices can be excited when the near-trapping of waves arises in a wave farm consisting of a circular array of OWC devices. The physical findings in this paper highlight the importance of the array configuration and opening arrangement for optimizing wave power extraction in wave farms.