Abstract

This paper investigates a method to determine the relative power
production potential of a floating oscillating water column wave energy
converter. This method focuses on determining the key characteristics of
the parametric function relating the water column heave velocity to the
structure heave velocity. The numerical investigation is undertaken using
single frequency sinusoidal waves using WAMIT and OrcaFlex.
The paired velocities of the structure and the water column surface
follow an elliptical function. The properties of this ellipse yields
interesting information about the power produced by the OWC. It has
been determined through investigation into the length and gradient of the
major (long) and minor (short) axes of the bisector of the ellipse that
relates the vertical water column heave velocity to the structure heave
velocity that the power production potential is linearly proportional to
the magnitude of of relative velocity between the water column and
floating structure more so than a phase difference between these two
velocities.
It has also been determined that the lengths of both axes of the ellipse are
maximised, and hence system efficiency, when the forcing frequency is
equal to approximately 90100% of the of natural frequency of the water
column of the system in question.