Multi-chamber cylindrical OWC: analytical model and numerical results

Abstract

Wave energy has the potential to play a crucial role in the ongoing energy transition towards the exploitation of renewable energy sources. Among the wave energy converters, Oscillating Water Column (OWC) is recognized to be one of the most promising technologies. Despite the amount of research conducted on those devices, there is no consensus on the optimal OWC configuration. In this context, circular OWCs emerged as an attractive option as it is a configuration unaffected by the direction of the incoming waves. Recently, research focused on devices equipped with multiple chambers in order to increase the overall device efficiency via the introduction of concentric chambers. This paper studies a multi-chamber concept arising from the partition of a cylindrical single chamber OWC into multiple chambers spanning a reduced inner angular width. Within the linearized potential flow theory, throughout the eigenfunction expansion matching method, and considering a linear power take off, a semi-analytical solution is obtained. Next, numerical results pertaining to the cases of a circular OWC comprising two and three chambers, spanning the whole inner sector, are discussed. The numerical analysis shows that the use of multiple chambers having a reduced angular width increases the overall energy-wise performance of the system with respect to the case of a single chamber OWC.