Experimental investigation on hydrodynamic performance of a dual pontoon-power take-off type wave energy converter integrated with floating breakwaters

As an extension of the single pontoon wave energy converter–type breakwater, a wave energy converter–type breakwater equipped with dual pontoon–power take-off system is proposed to broaden the effective frequency range (for transmission coefficient KT < 0.5 and capture width ratio η > 20%). The wave energy converter–type breakwater with dual pontoon–power take-off system consists of a pair of heave-type pontoons and power take-off systems for which the power take-off system is installed to harvest the kinetic energy of heave motion of the pontoon. In this paper, we experimentally confirm the advantage of the wave energy converter–type breakwater with dual pontoon–power take-off system over the one with a single pontoon–power take-off system. Both wave energy converter–type breakwater with dual pontoon–power take-off system and that with single pontoon–power take-off system are tested in regular waves. A (electronic) current controller–magnetic powder brake system is used to simulate the power take-off system. The characteristics of power take-off system are investigated and results showed that the power take-off system can simulate the (approximate) Coulomb damping force well. Experimental results reveal that the wave energy converter–type breakwater with dual pontoon–power take-off system broadens the effective frequency range compared with the single pontoon–power take-off system with the same pontoon volume (i.e. the displacement of the pontoon). Specifically, the transmission coefficient of the system is smaller while the system in relative longer waves. Furthermore, the capture width ratio of system can be improved.