Wave energy device, Oscillating water column, thermodynamics, orifice equation, test rig, servomotor, thermocouple.
In the development of the Oscillating Water Column (OWC) device, difficulties remain regarding the monitoring system and the scaling methods required for the characterisation of device performance. It is especially difficult to measure the water level in the air chamber and the flow passing through the turbine (or orifice at smaller scale). This leads to difficulties in analysing and understanding the device behaviour.
An experimental test rig at 1/50th scale has been built which is capable of recreating the thermodynamic conditions in an OWC and accurately measure the relevant physical quantities. A servomotor controls the motion of a piston through a cylinder, modelling the forcing water surface in the plenum chamber. An adjustable orifice fitted on the other side of the chamber models the behaviour of an OWC turbine or equivalent power take off mechanism.
In this paper, the engineering design and the operational results of this test rig are presented in detail and compared with a basic thermodynamic analysis for validation and further understanding. These results cast a new light on flow and temperature measurement methods and on the use of orifice for model testing.
In further investigations, this test rig, in parallel with a numerical model, will be used to look at scaling methods and orifice/damper design with passive and active control.