Effects of Dense Inert Particle Loading in Shocked Energetic Materials

Metal particles are often added to solid-fuel rocket motors and weapon systems to boost detonation propagation or to increase impact energy. Aside from the chemical effects of reactive particles, even inert particle effects can be significant on detonation properties due to the momentum and the energy exchanges between the phases. Therefore, a study of inert particles, that can exhibit direct effects on shock-to-detonation-transition (SDT) depending on particle loading and its material properties, is needed. This work numerically investigates the effects of dense inert particle loading on SDT in energetic material (EM). The focus here is on local non-equilibrium (NE) effects in particle-added EM mixture and its correspondence to observed parametric trends on detonation. An Eulerian-Eulerian (EE) framework capable of modeling dense-dilute particles is used within a well-established multi-phase solver to capture dispersed motion in a reactive condensed phase. The numerical approach is first validated against available experimental data, and this is followed by an investigation of particle effects over a range of parameters where a condition-dependent trend is observed. Focusing on the two-phase NE effects, the dynamic and the thermal disparities between particles and EM are quantified to demonstrate the effect of relaxation parameters on the observed detonation quantities. The reduction in peak pressure and detonation velocity is observed to follow NE strengths and corresponding relaxation rates. An assessment of the effects of various particle loading parameters, i. e., concentration, size, density, and specific heat, on SDT is performed along with quantifying the relaxation process. All particle loading parameters show a range-dependent effect on detonation properties, and the observed results demonstrate the relevance of two-phase NE and corresponding relaxation processes.