An Experimental Study on Primary Efficiency of a Wave Energy Converter "Backward Bent Duct Buoy" in regular wave conditions

A primary conversion efficiency of a floating OWC-type wave energy converter "Backward Bent Duct Buoy (BBDB)" in regular waves is investigated in 2D and 3D wave tank tests. Firstly, the amplitude and phase difference between the internal wave height and motions are investigated. In a 3D tank test, surge, heave and pitch become in-phase at efficiency become maximum. The phase of internal wave height is close to motion. Secondary, the efficiency of duct-extended buoy is investigated in 2D test. Efficiency is reduced because the pitch becomes small by duct extension. Thirdly, the effect of a moment of inertia is investigated. In case of total mass and draft is constant, frequency band of high-efficiency increases as the moment of inertia become large. Fourthly, the effect of the shape of the air chamber is also investigated.