| The study of particle breakage of the granular system in two-phase flow is a current issue of concern in many fields,this issue is of great significance for the study of the safety of launching charge.The crushing of the propellant bed is the core problem to evaluate the safety of launching charge.Using the discrete element method to simulate the crushing of particles,granular systems and internal particles is the general research of this,and the dynamic extrusion model is used to replace the fuel gas propulsion in practical engineering,without considering the complex process of fluid action.The innovation of this paper is to reduce the gas impact load in practical engineering,and the complex gas-solid interaction is considered in the motion study of the propellant bed.In this paper,with the background of the big issue of the safety of launching charge,gas-solid two-phase model is established based on discrete element method and computational fluid dynamics respectively,numerical simulation of particle breakage in two-phase flow is carried out,and apply it to the study of fracture process of the propellant bed under the impact of high-speed gas,the specific research contents of this paper are as follows:(1)Calculation model for particle breakage in gas-solid two-phase flow is established.Firstly,particle breakage of the granular system model where separate particle can be broken is established,then a gas phase model in the cylinder is established,finally gas-solid model information is exchanged through a coupling module and gas-solid two-phase model that can describe particle breakage is established.(2)The effects of different discrete method,particle shape and packing density on the gas phase distribution and particle breakage in two-phase flow are compared.Internal relations and law of changes in regular/random discrete particles,cubu/sphere/regular hexagonal prism particles and different packing densities of particles with two-phase system are revealed from the perspective of solid phase and gas phase systems.(3)The discrete element model of propellant grain is established and the micro parameters are calibrated to verify that the discrete element model of propellant grain can effectively simulate the mechanical behavior of the actual propellant grain,a numerical model for ammunition impact crushing system in two-phase flow is established and numerical calculation is conducted.The conclusions drawn through numerical studies are:(1)The discrete method,particle shape and packing density have significant effects on the solid-phase system in two-phase flow.The breakage rate of regular discrete particles is higher than that of random discrete particles,the breakage rate of cubu particles is higher than that of regular hexagonal prism and sphere particles in turn,the breakage rate of particles with low packing density is higher than that of high packing density.The particles with high breakage rate have better polymerizability and the particle speed increase more slowly.(2)The discrete method,particle shape and packing density have significant effects on the gas-phase system in two-phase flow.When the internal flow field tends to be stable,the gas pressure and velocity of regular discrete particles are higher than that of random discrete particles,the gas pressure and velocity of spherical particles are higher than that of regular hexagonal prism particles and cubu particles,and the gas pressure and velocity of high packing density particles are higher than that of low packing density..(3)Compared with the physical test,change of motion state of the propellant bed,degree of breakage and breech pressure are analyzed.The calculation shows that the error of the combustion surface area of the propellant bed is 5.65%,and the error of breech pressure is3.34%.Considering the possible errors caused by the simplification of the model and the limitation of the internal packing density,the numerical experiment can perfectly reproduce the crushing process of the propellant bed in two-phase flow. |
PDF Full Text Request