Theoretical Modeling And Numerical Study On The Mixing Of Metal Particles With Gas Under Detonation Driven Conditions

When an extreme shock wave releases from the free surface of the metal material, some high speed particulate matters will be ejected from the material body and enter into the background gas. This induced multiphase mixing phenomenon is known as the ejecta mixing. The research of ejecta mixing is of great significance for understanding the influence of mixing on the compression process under high temperature and high pressure conditions, and optimizing the design of implosion engineering.Theoretical modeling and numerical simulation of ejecta mixing is a difficult and hot issue that needs to be solved urgently in the field of inner explosion compression, and it involves the cross study of multiphase fluid mechanics, heat and mass transfer, computational mathematics and so on. In this paper, we review the research in system, and then focus on the ejecta mixing by detonation driven. The study of theoretical modeling and numerical simulation in different stages will be carried out, and the analysis of the gas particle mixing development patterns and the influence on the implosion compression process will be given.In the early and middle stage of detonation driven, the gas particle interaction is investigated based on the typical flow conditions. The dominated force and heat transfer are identified, and the relaxation characteristics are obtained. In order to obtain the details of ejecta movement, the particle trajectory model is chosen as the basic model, and then the governing equations including interactions between gas phase and particle phase are derived. For giving the specific calculation formula, the physical meanings of the coupled interaction source terms in the Lagrangian framework are analyzed and a stable numerical scheme is given based on the staggered strategy. We also devise two different computing models of ejecta mixing, the planar and the column configurations, and then the numerical simulations are carried out. The phenomenon of gas shock speed acceleration caused by particle feedback is found, and the distributions of the physical quantities in the gas area are changed. Especially for the convergent configuration, the feedback effects will be amplified further by the geometrical shrinkage, which may have a significant influence on the performance of the inner explosion compression, owing to the obvious uniformity variation of the gas flow field and the gas shock rebound in advance.In the middle and late stage of detonation driven, we aim at the problem of the propagation behavior of reflected shock wave in the ejecta mixing flow and the compression properties in the convergent geometry. The applicability of the two fluid model is studied. We are dedicated to developing the computational model under dense condition. The space volume occupied by particle phase and the interaction between particles are overall considered. A new formula of isentropic sound speed is derived. The variations of sound speed with different mass fractions of particle phase are analyzed. Furthermore the corresponding physical principles and the mechanisms are discussed and revealed. Numerical simulation of the shock wave propagation in an ejecta mixing flow is carried out, and the dynamic behaviors under different particle mass fraction are obtained. The characteristics and the law of the convergent compression of the ejecta mixing flow are studied, in the case of typical particle distributions and different ejection quantities. It is found that the ejection quantity is the key physical factor to influence the compression of the ejecta mixing flow.