Numerical study of a novel flex mooring system of the floating wave energy converter in ultra-shallow water and experimental validation

In order to cope with design difficulties of the mooring system of the floating wave energy converter (WEC) in ultra-shallow water under typhoon sea state, while remaining economically feasible and reliable, new mooring system design strategies need to be implemented. The present paper aims at summarizing these design strategies of mooring system and proposing a novel mixed superflex wire rope design for WEC mooring system. By comparing with the traditional low elastic polyester ropes and hybrid catenary chain mooring system, it has been found that adding high elastic cable such as superflex rope and buoy can effectively improve the reliability of the mooring system and the energy storage of the WEC. The numerical model demonstrated a good, reliable and effective agreement with the experiment with the present superflex design. The present mixed superflex rope mooring system can effectively reduce the mooring radius, the length of mooring line and material usage as well as max mooring tension. Thanks to the good elasticity of the mooring system, the transient extreme mooring tension can be effectively reduced and the survivability of the device can be improved. This experience proposes significant improvements for other mooring system design of floating WEC design in ultra-shallow water.