Effect of Harbor Walls on the Efficiency of an Oscillating Water Column

Abstract

Among the numerous wave-energy converters (WECs), the oscillating water column (OWC), which runs on the concept of capturing energy from the rise and fall of the water column in a closed chamber resulting from wave motion, has become quite popular. The compressed water column in the chamber advances an air stream that can drive a turbine coupled to electric generators. The present study aimed to investigate the influence of the projecting sidewalls, or so-called harbor walls, of an OWC on its energy-efficiency characteristics. The design and optimization of the harbor wall’s projecting length and its inclination are as important as the hydrodynamics of waves inside the chamber, apart from the characteristics of the air vent and the turbine parameters, which play a critical part in the performance of these devices. The objective of the present study was to optimally convert the incident wave-energy into pneumatic power by analyzing the influence of projecting sidewalls and optimizing the length and inclination (opening angle) of the walls. The projecting length was varied in terms of the ratio of the harbor wall length (c) to the breadth of the OWC (b) (c/b = 1, 1.5, and 2). The inclination of the harbor wall was varied in the range of (π/2, 7π/8) at an interval of π/8 with respect to the front lip wall of the OWC.