Investigation Of Hydrodynamic Characters For A Single-point Moored Floating Liquefied Natural Gas(FLNG) Facility

This paper has investigated the hydrodynamic characters of a SPM FLNG facility through the methodology of model tests and numerical simulations. In model tests, the models of FLNG vessel, SPM system and liquefied natural gas tank have been made according to the original design. Through the tests of extinction in calm water, the natural periods and damping coefficients of the FLNG vessel have been acquired. The horizontal restoring force of SPM system in model test has been compared with the original design. In the model tests, the Response Amplitude Operators are calculated from the response spectra of the FLNG vessel in white noise wave. Moreover, the model tests were conducted for the FLNG system subject to 1-year return and 100-year return sea conditions lasting for 3 hours in the South China Sea. To consider the coupling response of the FLNG facility, those results in time domain are obtained with the FLNG vessel positioned through the SPM system. Time histories of the motion responses of the FLNG vessel and the maximum values of top tensions on the hawsers were obtained and translated into the prototype. Investigations of the effects of various sea conditions and inner tank sloshing on the FLNG’s motion responses have been conducted.Numerical model of FLNG has been established through the verification of the results from model tests. Moreover, the horizontal stability of the FLNG facility is investigated through numerical simulations. In the numerical model, inner turrets with different longitudinal locations have been created, through which the FLNG vessel is connected with SPM system. The investigation of the effects of different turret’s locations on the horizontal stability of the FLNG facility has been conducted. A suggestion of the reasonable locations of inner turret has been provided. Through the case in which certain mooring line was broken in numerical simulation, the redundancy of the original SPM system has been studied. Furthermore, an optimized SPM system has been proposed according to the original design to reduce the potential expense of fabrication. The safety of this optimization has been investigated through further numerical simulation.This paper has conducted investigation on the hydrodynamic characters of a SPM FLNG facility, which will provide a brief of principles with more details for the design of the ongoing project.