Experimental Study on Conversion Characteristics of Dual-Mode OWC Models Appropriate for Voyaging

Freely movable wave energy converters (WECs) will greatly improve their adaptability to the marine environment. In this paper, a dual-mode oscillating water column (OWC) WEC with potential sailing capability is proposed. By opening and closing a gate on the side facing the waves, the WEC converts wave energy in the vertical duct (called VD mode) with low sailing resistance or in the backward bend duct (called BBD mode) with high sailing resistance. A small model and a medium model were designed and manufactured. The capture width ratio (CWR) of the small model in the two modes was experimentally studied. The CWR under bidirectional airflow and conversion characteristics under unidirectional airflow of the medium model in the BBD mode were obtained. Tests of the small model show that the peak CWR is 145.2% under regular waves and 90.1% under random waves in BBD mode, and in VD mode the peak CWR is about 60% of that in the BBD mode. Tests of the medium model show that the peak CWR is 228.96% under regular waves, the maximum wave-to-battery efficiency is 63.36% under regular waves and 30.17% under random waves, respectively.