A modified version of the Edinburgh duck wave energy converter has been studied recently at the University of Edinburgh. From the design point of view the key innovation was a modification of the wetted profile. Wave energy is converted into useful work by the same pitching motion as in the original duck, but by means of a circular cylinder with an off centred axis of rotation. This recent study was focused on a duck version designed for vapour compression desalination rather than electricity production. The duck was partially filled with water and the motion of the water inside provided the necessary pump effect for the vapour compression. The inner water behaves as an inertial reference as well as a double-acting piston. Under the assumptions taken, the results can be applied also to the electricity production version.
WAMIT was used to predict the hydrodynamic coefficients and to select a set of configurations. A 1:33 scale model was tested at the Edinburgh curved tank to validate the numerical predictions.
This paper extends the already published numerical predictions and experimental results obtained with this model, and reports on the new experimental tests and features. The relative capture width of the device that resulted from the measurements is presented, as well as the measured mooring forces in regular waves. Finally, the behaviour of a linear damper used to model the power-take-off mechanism is analysed.