Study On The Coupling Effects Of FPSO Ship Motion And Nonlinear Tank Sloshing

With the development of ocean resources,FPSO is more and more widely used.In the exploitation and transportation of offshore oil and gas resources,the coupling interactions of wave motion,ship motion and tank sloshing are inevitable.In the present study,the influence of tank sloshing on ship motion is often neglected or linear.In fact,the nonlinear coupling between ship motion and sloshing is very significant is extremely significant.In this paper,the CFD software FINE/Marine is used to simulate the three-dimensional numerical simulation of the coupling between the FPSO tank and the ship motion in the wave.The external flow field(wave field)and the flow field inside the tank(nonlinear liquid sloshing)are calculated based on viscous flow theory and hydrodynamic theory(CFD).Viscous flow theory is used in a wide range,it can simulate more physical phenomena.At the same time,it can also solve the strong nonlinear problem of sloshing in liquid tank and ship motion under the action of large amplitude.In this paper,the coupled motion of sloshing in liquid tank and FPSO is studied in detail.The main achievements of this paper are as follows:(1)The research methods of ship motion prediction in waves are briefly reviewed.The simulation methods of tank sloshing are briefly reviewed.And make a system introduction about the research methods and the latest research progress of the coupled motion of tank sloshing and ship motion.(2)The interaction analysis equations of the tank sloshing and the ship motion is established.Based on the viscous flow theory,numerical calculation methods of the interaction between ship motion and tank sloshing are introduced systematically.The flow and method of CFD platform FINE/Marine are discussed systematically.And make a system introduction about the calculation process and methods of CFD software FINE/Marine.(3)Based on the viscous flow theory,the numerical simulation of single tank sloshing is carried out.The calculated results are in good agreement with the experimental results in the literature.At the same time,the grid convergence analysis is carried out,and the optimal meshing scheme is selected to provide a reference for the calculation of the interaction between FPSO ship motion and tank sloshing.(4)Based on the viscous flow theory,the numerical pool is established.On the basis of verifying the correctness of the wave-making pool,the numerical simulation of the free float in waves is completed and compared with the experimental results,to further explore the effects of different wave periods and different wave heights on the response of ship motion.(5)Based on the nonlinear time domain viscous flow theory,the motion response of FPSO with nonlinear tank sloshing is studied.To explore the effects of tank sloshing effects,the motion response of FPSO with tank and without tank in beam waves and head waves is analyzed numerically.The effects of the carrier velocity and the external wave factors such as the wave frequency and the amplitude on the FPSO motion are further discussed.The numerical simulation analysis of the ship motion with low carrier capacity in the case of large amplitude is carried out.Under the condition of full coupling between ship motion and tank sloshing,the turbulence of the fluid in the tank and the pulse pressure of the bulkhead are observed.