Analysis Of Sloshing Characteristics Of Solid-Liquid Two-Phase Flow In Liquid Tank

Liquid sloshing refers to the movement of two or more immiscible substances in a limited space and there is a free surface(boundary)that can move freely and has the characteristics of strong nonlinearity and randomness.Mixed media exist widely in nature,while solid-liquid mixed media exist widely in chemical industry,food processing,sewage treatment,metallurgy,pharmaceuticals,ship and marine engineering and other important industrial fields.With the development of oil,gas,mineral exploitation in offshore engineering and offshore aquaculture,people pay more and more attention to the movement of solid-liquid two-phase flow and its coupling with the supporting structure during transportation.Due to the presence of solid,its sloshing characteristics are much more complicated than those of a pure single-phase fluid.How to establish a calculation and analysis method to solve the problem of solid-liquid two-phase flow in a liquid tank under external excitation and reveal its sloshing mechanism is of great scientific research significance and obvious engineering application value.Based on the theory of multiphase flow,a computational model of the sloshing motion of gas-liquid-solid multiphase flow in a liquid tank is established in this paper.The gas-liquid two-phase fluid is used as a continuous phase,and the Euler method is used to describe its motion,and the VOF method is used to capture the motion of the gas-liquid interface,i.e.the free surface.Solid particles are treated as discrete phases and their motion is described by the Lagrange method.The coupled motion of two-phase fluid and solid particles is numerically calculated by the CFD-DEM coupling method.Taking the multiphase flow of gas-water-ice particles as an example,the influence of ice particles in the tank on the sloshing characteristics of the tank is calculated and analysed using the STAR-CCM+ software platform.The main work and conclusions of this paper are as follows:1)The sloshing of pure water tank is numerically simulated and compared with the open test results,which verifies the feasibility and effectiveness of the numerical method of gas-liquid two-phase fluid sloshing,and analyses the free liquid surface overturning and crushing under two-dimensional large sloshing.Then,the gas-liquid two-phase fluid sloshing under forced excitation is studied.When the excitation frequency is close to the natural frequency or the rolling angle is large,the sloshing of the tank is more intense,which is manifested by the increase of the free surface wave height and the double peak phenomenon of the tank wall pressure,which shows strong nonlinearity.2)The sloshing characteristics of ice-water two-phase flow are studied by comparing and analysing the bulkhead pressure and free surface motion amplitude caused by the sloshing of ice-water two-phase flow at different volume fractions.The calculation results show that as the solid volume fraction increases,the fluctuation amplitude of the liquid level decreases,which indicates that floating particles have an obvious inhibiting effect on tank sloshing.3)The influence of different solid particle densities on the tank is calculated and analysed.It is found that the solid particle density of 910kg/m3 is better than that of1025kg/m3 and 2450kg/m3,and the sloshing suppression effect of the tank decreases with the increase of solid particle density.With the increase of solid particle density,the possibility of particle-to-particle collision and particle-to-bulkhead collision decreases.4)The sloshing characteristics of solid-liquid two-phase flow tanks with different excitation frequencies are calculated and analysed.The results show that the suppression effect of solid particles on tank sloshing is more obvious in the case of large sloshing,and the suppression effect is better in the stable state of small sloshing.5)The effects of different excitation frequencies and different rolling angles on the sloshing characteristics of solid-liquid two-phase flow under forced rolling are calculated.As the excitation frequency approaches the first order natural frequency and the rolling angle increases,the liquid moves more violently.In addition,the possibility of particles hitting the bulkhead increases,resulting in negative pressure and sudden pressure changes at the bulkhead of the liquid tank.