Numerical simulation on an anti-typhoon constant tension mooring system of wave energy devices

Abstract

In order to maintain constant tension under bad sea conditions, this paper proposes a constant tension mooring system that releases kinetic energy through the moving distance of the floating body applicable to floating wave energy devices. An effective mooring retraction scheme is created to ensure that the maximum instantaneous mooring force will never exceed the breaking force of the mooring line. On the basis of the time-domain potential flow theory, the coupled dynamic response of a 260 kW eagle wave energy device and a constant tension mooring system deployed at 28 m depth is studied under the condition wind and wave current in the South China Sea. The influences of anchor chain size, layout, and installation cost are analyzed. Compared with the traditional catenary mooring system, the proposed constant tension mooring system can effectively reduce the length of the anchor chain, material consumption, and maximum tension of the mooring line. It also avoids damaging the mooring line and its structure due to excessive forces because it maintains a basically constant tension and can, therefore, effectively improve the survivability of wave energy devices during typhoons.