The Numercial And Experimental Study On Motions Of The FLNG Ship Coupled With Tank Sloshing

Liquid sloshing in tank is excited by the global motion of the liquid cargo vessel,meanwhile the loads induced by sloshing act on the vessel reversely and affect the global motion of vessel.The coupled problem between tank sloshing and vessel motion become more severe with the increase of vessel size and improvement of operation efficiency and security of vessel.It concerns three aspects: ship motion,tank sloshing and coupling motion of sloshing and ship for solving the problem.In this paper,it separately introduces the ship motion theory and tank sloshing theory.Then,we establish an equation of ship motion for considering the effect of tank sloshing in frequency domain.At first,based on 3d potential flow theory and radiation/diffraction theory,it develops the computational procedure using the higher-order BEM(Boundary Element Method)which can compute the force and motion of 3d floating structures induced by wave.To verify the accuracy of the computational procedure,it compares the numerical results of a FPSO(Floating Production Storage and Offloading)with the results computed by the hydrodynamic software: Hydrostar and AQWA.And it provides the basis for the hydrodynamic computation of tank sloshing.To consider the computational accuracy and efficiency,it establishes the equation of ship motion with the effects of tank sloshing by combining the method of the hydrodynamic computation of tank sloshing to the method of ship motion’s computation in frequency.The motion response of an LNG-FPSO with two partially-filled tanks are obtained in regular wave conditions,and the solutions are compared with experimental results.Through the present work,it can be shown that the ship roll resonance frequency is to be shifted because of the tank sloshing,several roll peak values appear and the different effects are caused due to different tank filling levels.By carrying out ship model rolling experiments,the motion responses of ships under different working conditions such as draft,number of loading tanks and loading rate of tanks are studied.The influence of tank sloshing on ship motion response is fully analyzed and studied,which provides some reference value for the motion design of liquid-carrying ships with tank sloshing.