Numerical analysis of initial cloud of powder dynamic dispersion

Abstract

Numerical simulations were performed to investigate the explosion dispersion characteristics of powder materials with respect to the implicated velocity, and a fluid–solid coupling simulation model of the explosion dispersion process of the initial cloud was established. Explicit dynamics models of Finite-element method and smooth particle hydrodynamics for the detonation driving stage of central charge and the cloud isentropic expansion stages were developed, the pressure loads of the explosive-driven were generated using the user-defined function program, and computational fluid dynamics models for the isentropic expansion and free expansion stages of the initial cloud were developed. Additionally, the maximum expansion radius of the cloud in explosion dispersion tests and theoretical calculations were compared with the radius in the numerical simulation results to verify the accuracy of the simulation model. Analyses of the morphology, concentration, and turbulence field in the numerical simulation revealed that vortex stratification occurred in the “two wings” of the initial cloud in its development process and that a particle-free “hollow” area is subsequently formed. Analyses also revealed that the vortex stratification occurs earlier as the implicated velocity of powder material increases. Additionally, an increase in the implicated velocity can effectively weaken the concentration of cloud and make the distribution of cloud particles more uniform.