Study On The Effect Of Suppressing Liquid Sloshing In FPSO Cargo Tank

FPSO is known as the "offshore oil factory" because of its advantages in the primary processing and storage of oil extracted from the seabed.During operation,the FPSO will be excited by external excitation in multiple directions and move,causing the liquid in the tank to slosh.When the external excitation frequency is close to the low-order natural frequency of the liquid in the tank,the liquid in the tank will slosh violently.The sloshing liquid will produce a huge impact load on the tank structure,and in severe cases will cause damage to the bulkhead.According to different working conditions,this paper studies the sloshing problem of sloshing liquid in the FPSO tank.The main work is as follows:1.Taking the 300,000-ton FPSO medium cargo tank as the prototype tank,taking the oil products in the tank as the research object,combining the similarity theory,choosing the Reynolds number and the Froude number as the similarity criterion numbers,and selecting the appropriate scale ratio to build the model And derive the density and viscosity of the corresponding experimental oil.2.Combining the actual work of the FPSO,using the VOF method to track the free liquid surface,and combining the dynamic grid technology to establish a three-dimensional liquid cargo tank sloshing numerical model,simplifying the movement of the liquid cargo tank in the FPSO to forced swelling under external excitation Movement,simulation of the liquid sloshing process in the liquid cargo tank in the FPSO,combined with other model test data,verifies the accuracy of the numerical model in this paper.3.Based on the established numerical model,taking the tank with vertical partitions installed at the free liquid surface as the research object,studying the sloshing characteristics of the liquid in the tank at the more dangerous first-order natural frequency,mainly analyzing the free liquid surface waveform process,The time domain and frequency domain characteristics of the impact pressure of the sidewall sloshing are compared with the results without the diaphragm,and the sloshing effect is obtained.Through comparative analysis,it is found that when the tank is not added with partitions,the liquid in the tank will slosh violently,and the sloshing impact pressure can reach very large strength,and there are large fluctuations between peaks,and the slamming range is wide.Basically,the entire tank is uniform.Suffered from slamming;after adding vertical partitions,the wave surface in the tank was much smoother,the pressure peak fluctuates little,the slamming force is significantly reduced,and the impact range is reduced to near the free liquid surface and below the static water surface.4.On the basis of studying the sloshing effect of adding vertical partitions to rectangular cargo tanks,according to different external excitation amplitudes and liquid loading conditions,the effect of the solids rate of the partitions on the liquid in the tank under the excitation of the first-order natural frequency is analyzed.The impact of the swing effect.Through comparative analysis of the evolution process of the free liquid surface waveform,the evolution process of the flow field in the liquid phase,the time domain variation curve,frequency domain and energy spectrum characteristics of the sloshing impact pressure of the tank side wall,the effect of the solid rate on the oscillating effect is obtained.