Influence Of The Sloshing Hydrodynamic Load On The Tank Structure Of FLNG

For the development mode of the deep-sea natural gas,the purification,liquefaction,storage and offloading are important engineering segments.In order to integrate the above functions,a key equipment of Floating Liquefied Natural Gas Production Storage Offloading System(LNG-FPSO)can be applied in the exploitation of natural gas.Furthermore,Floating Liquefied Natural Gas Storage Regasification Unit(LNG-FSRU)is a new ocean engineering equipment which can combine LNG vessel with regasification equipment and satisfy daily requirement.LNG-FPSO and LNG-FSRU are both called as Floating Liquefied Natural Gas(FLNG).Under various deep-water wind,wave and current,the LNG storage tank should be in difficult six Degree-Of-Freedom motions along with FLNG.Furthermore,when the storage tank is partly filled,there are serious sloshing phenomenon of LNG in tank,which should induce sloshing loads and result in the impact failure of tank structure.At present,the abilities of design and manufacture about domestic companies should be improved.Thus,the research on the LNG sloshing loads and tank structure has important engineering safety and economic significance,which can provide theoretical reference for safe and efficient operation of FLNG.In order to study the influence of FLNG tank structure on sloshing load,this paper analyzed the motion characteristic of FLNG in wave based on wave potential theory and numerically simulate the sloshing loads on tank structure by means of CFD method.The detail contents include as follows.(1)This paper created a classic hydrodynamic model of FLNG.Then the wave load and motion characteristic of FLNG are calculated based on wave potential theory,which are validated and compared with the results of model test.On this basis,the classic motion responses of FLNG and LNG tank are analyzed.(2)According to the data of sloshing experiments,the sloshing phenomenon in LNG tank is studied by VOF explicit multiphase model.Free surface,roll moment and pressure distribution of LNG by numerical method are compared with experimental results,which shows the accuracy and feasibility of numerical method and model of LNG sloshing in this paper.(3)Based on numerical model and method of this paper,LNG sloshing hydrodynamic force on tank structure can be simulated,and then classic motion state of LNG tank and sloshing load can be numerically simulated.By sloshing models versus different heights and holes of damping structure,the effect of motion responses and periods on the hydrodynamic force of tank structure can be studied.Therein,tank structure,natural frequency and sloshing load are mainly discussed.In this paper,the research conclusions and results about the motion characteristic of FLNG and sloshing theory of LNG can be studied,which can provide the theoretical reference and guidance for the design of tank structures of large-scale FLNG.