This paper presents a preliminary investigation by numerical modelling into the importance of the air chamber design of an OWC wave energy device, with respect to its principle dimensions in the overall optimisation of the power conversion properties. A fixed, twodimensional, frequency domain model for finite water depth is used to describe the system behaviour. Global optimisation techniques have been applied in order to determine the maximal efficiency with respect to the following five free design parameters: submergence of the barrier, length of the chamber, height of the chamber above the water surface, diameter and rotational speed of a specific turbine design class. Wave spectra from the Pico site were used to represent the sea conditions.
The Oscillating Water Column (OWC) is the wave energy converter that has received most attention with regard to theoretical device modelling, as well as in experimental testing and the development of practical prototypes. The state of the development has reached a level where the functionality and practicality of the principle have been proven and the theoretical descriptive models have become reasonably sophisticated. Existing work on device modelling and component optimisation has tended to concentrate on the hydrodynamics and on the turbine employed for power take-off. Attempts have also been made to optimise the behaviour of the device with regard to its hydrodynamic characteristics and turbine behaviour. However, there is clearly a technological gap in the modelling of the physical phenomena in the domain that interconnects the motion of the water surface and the turbine. In the context of optimisation it is crucially important to be able to deal with complete system models rather than with models of subsystems. In order to obtain a sufficiently accurate system model, both hydrodynamic and aerodynamic subsystems have to be coupled accurately.
