Modeling of particle compressibility and ignition from shock focusing

Abstract

Two-phase shock-driven reacting flow simulations are conducted to determine the postdetonation shock-focusing ignition and burning of aluminum particle mixtures. A model for aluminum particles that accounts for material compressibility from shock heating and expansion is presented. The Lagrangian description of the particles is incorporated into an Eulerian description of the gas phase resulting in a fully compressible, twoway coupled simulation. Simulations are conducted of an isolated explosive located near a corner to promote ignition of the particles from shock focusing. Parametric studies are conducted to determine the effects of equivalence ratio, particle size, and charge placement, on the post-detonation pressure and impulse. Results highlight the importance of the timing and position of the shock focusing event relative to the local mixture equivalence ratio that results in an optimal equivalence ratio which maximizes impulse for the geometry considered.

Effects of the aluminum content on the shock wave pressure and the acceleration ability of RDX-based aluminized explosives

“…In the figure, the pressure impulse increased with an increase in the equivalence ratio from 0 to 0.95. Ruggirello et al 42,43 also got a similar conclusion by numerical simulation. However, an optimum value of equivalence ratio is not found because the study examined only three types of aluminized explosives.…”

A Cell-Centered Multiphase ALE Scheme With Structural Coupling

“…This added stress results in non-equilibrium between the gas and particle pressures. Many researchers have discussed the importance of compaction on multiphase dynamics [18,[69][70][71].…”

A reaction progress variable modeling approach for non-ideal multiphase explosives

“…Most recently, Washburn et al (2008Washburn et al ( , 2010 have combined the Liang/Beckstead (Liang and Beckstead, 1998;Widener et al, 1998) model with a detailed chemical-kinetics mechanism and direct numerical simulation (DNS) of the gas phase around the particle to examine the combustion characteristics for a range of oxidizing and pressure environments. In the current study a previously developed aluminum particle combustion model (DesJardin et al, 2005;Ruggirello et al, 2010) is used which relies on Shvab-Zel'dovich coupling functions (Kuo, 1986) to efficiently solve the coupled heat and mass transfer for the particle.…”

“…To recast the previously developed Lagrangian aluminum particle combustion model (DesJardin et al, 2005;Ruggirello et al, 2010) into an Eulerian framework, a reaction progress variable description is used. An Eulerian framework for the aluminum particles is chosen because of the desire to account for the group combustion burning mode for aluminum rich charges.…”

“…where b P and l c are defined as the configurational pressure and l c is the compaction viscosity (Ruggirello et al, 2010). This model is a direct particle model analog to the compaction model of Baer and Nunziato developed for mixtures.…”