Halona functions as an omnidirectional spar buoy oscillating water column (OWC) wave energy converter (WEC). The buoy consists of a cylindrical spar, a heave plate at the base, and four axisymmetric waveguides. The overall design features are intended to improve buoy stability for autonomous underwater vehicle (AUV) docking. Objective: To understand the power performance and motion response of Halona for the purpose of improving the state of WEC based AUV docking. Halona has yet to be optimized for power extraction. As Halona is designed for AUV docking, dynamic positioning and motion control will be needed, which require an in-depth understanding of motion response in multidirectional irregular waves. Methods: A 1/10th scale Halona was tested in unidirectional regular waves with a range of power take off (PTO) damping values represented by different diameter orifice plate dampers. Halona was tested at the O.H. Hinsdale Wave Research Laboratory Directional Wave Basin in a scaled version of the design field conditions. The eventual field deployment will occur at Kilo Nalu on the south shore of Oahu, which is a strongly bimodal wave condition, with distinct wind and swell conditions and minimal seasonal variability. Halona was also tested in directional waves to understand directional motion dependence. The directional dependence was determined for each orifice. Results: The resonant frequency of Halona was determined for both a free floating and fixed configuration. It was determined that the directional dependence of the incident wave is insignificant. The impact of the PTO damping on WEC motion and power performance was determined for the target operational wave conditions.

This project was supported during RFTS 1.