Numerical and experimental research on a resonance-based wave energy converter

Abstract

Inefficiency and intermittency caused by high variabilities of wave properties are common problems in existing wave energy technology. Resonant wave energy conversion technology can effectively solve these problems. However, the nonlinearity induced by the wave energy converter’s radiation and operation inhibits the resonance. After weakening the nonlinearity by hydrodynamic optimization and operation manner design, a novel wave energy converter that can realize resonance was proposed. In this paper, it is verified that this wave energy conversion system is close to linear, even in the case of large amplitude oscillation. For the novel wave energy converter, a radiation hydrodynamic parameter testing method is proposed, which provides parameters to accurately control the wave energy conversion system to achieve resonance; a wave force testing method is proposed, which can provide in-situ wave information to control resonance and judge resonance state; the effects of resonance, damping and nonlinearity on wave energy conversion are revealed, which provides a theoretical basis for the design of wave energy converter. Experimental studies showed that the laws of wave energy conversion are basically the same in regular and irregular waves, the methods and laws investigated in the regular waves also apply to irregular waves. And experiments also showed that the novel wave energy conversion system could be controlled to achieve resonance truly, and the novel wave energy converter can achieve resonance and highly efficient wave energy conversion in different wave conditions. The novel wave energy converter can self-perceive the wave changes and actively control its natural period to achieve resonance with incident waves, thus significantly increasing the wave energy conversion efficiency and improving intermittency.