Water Oscillation Modelling Inside OWC Chamber for Wave Energy Conversion

Abstract

Among wave energy converters (WECs), the Oscillating Water Column (OWC) system is considered as one of the most promising converters; this system works on the principle of water oscillations in an enclosed air chamber due to incident sea waves. The amount of pneumatic power that can be harvested depends on the elevation level, the water oscillations' frequency inside the chamber, and the chamber's global damping. A one-dimensional (1-D) unsteady model has been elaborated to analyze the water elevation's dynamic behavior. Great attention has been paid to determining the natural frequency and the global damping for maximum wave energy capture. The model is based on a water mass block moving periodically upward and downward as a piston inside the chamber, inducing the enclosed air to flow alternately through a turbine. The Lagrangian formalism has been adopted to derive the governing differential equation for the piston water motion. Then the poincare-Lindstedt method has been used to deal with the non-linearity of the problem. The elaborated model has been adapted to an OWC system in the case of monochromatic waves. Results have been compared to another referenced paper for validation and pertinence. Fair agreements have been noted.