Point absorbers are currently one of the main categories of wave energy converters being developed worldwide. These devices are classified by their dominant mode of motion relative to the water surface, that is heaving, surging or pitching. Most of these converters use either a hydraulic system or direct drive electric generator as a means for power take-off (P.T.O.). These wave energy devices are highly suitable for intermediate depth offshore locations.
This paper presents the preliminary results from an experimental study on the power capture of bottompivoted pitching cylinders in intermediate water depth subjected to regular and irregular waves.
The geometry of the pivoted cylinder, external damping and additional inertia (to simulate the impact of water ballasting) were taken as variable parameters in order to optimize the power capture efficiency in different wave conditions.
Wave tank simulation of EMEC (European Marine Energy Center) measured wave climate enabled us to obtain an understanding of the true hydrodynamic behavior and a reliable estimation of the possible power output from devices in operation.
The present research investigates the respective influence of critical parameters such as geometry, damping and ballasting of wave energy converters in order to maximize their efficiency in real sea states. By employing canonical shapes such as vertical cylinders, as opposed to specific designs, the aim of this study is to reveal the fundamental behaviour, which may then assist the development of more complex and efficient devices.
