Wave Loading on a Moored OWC Wave Energy Device

This paper describes results from wave tank testing on a 1/25 scale model of a moored oscillating water column (OWC) wave energy device. The device incorporates a piece-wise linear parabolic wall to focus the waves onto a three-sided OWC chamber. Model tests were conducted to determine the mooring line loads and associated structure motions in both a taut-moored floating configuration and a semi-fixed configuration. All six degrees of motion were recorded continuously along with forces in twelve mooring lines. Tests were conducted for a range of wave conditions and angles of incidence. For a device with a 35m wide parabolic wall (prototype scale), peak mooring line forces below 350Te were measured. In extreme conditions, heave motions were found to exceed design requirements in the floating configuration but this was rectified in the semi-fixed configuration. The paper presents a summary of the average results found and some of the dynamic response characteristics of the structure in various sea conditions. Implications for full-scale design and operation of the device are also discussed.