A complete equation of state for non-ideal condensed phase explosives

Abstract

The objective of this work is to improve the robustness and accuracy of numerical simulations of both ideal and non-ideal explosives by introducing temperature dependence in mechanical equations of state for reactants and products.To this end, we modify existing mechanical equations of state to appropriately approximate the temperature in the reaction zone. Mechanical equations of state of Mie-Grüneisen form are developed with extensions, which allow the temperature to be evaluated appropriately, and the temperature equilibrium condition to be applied robustly. Furthermore the snow plow model is used to capture the effect of porosity on the reactants equation of state.We apply the methodology to predict the velocity of compliantly confined detonation waves. Once reaction rates are calibrated for unconfined detonation velocities, simulations of confined rate sticks and slabs are performed, and the experimental detonation velocities are matched without further parameter alteration, demonstrating the predictive capability of our simulations. We apply the same methodology to both ideal (PBX9502, a high explosive with principal ingredient TATB) and non-ideal (EM120D, an ANE or ammonium nitrate based emulsion) explosives.

Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavities

“…[2][3][4] to govern the reactant and products of liquid NM does not adequately describe the physics in the reaction zone and the subsequent flow expansion. In future efforts, following the approach proposed by Wilkinson et al 69 , the EoS for NM reactant and reaction rate model can be calibrated using the up-to-date gauge measurement data, and the product EoS can be obtained by fitting to the principal adiabat calculated by an ideal detonation code such as IDex. Simulations treating the reactant and product of an explosive as two miscible materials governed by different EoS can be implemented using the MiNi16 formulation 35,70 .…”

Validation of a detonation product equation of state for an insensitive high explosive via slab geometry expansion tests

“…By far, the most commonly calibrated detonation product EOS model is the Jones-Wilkins-Lee (JWL) EOS form, which has been calibrated for a large number of HEs, for instance, cyclotrimethylenetrinitramine (RDX), cyclotetramethylene-tetranitramine (HMX), triamino-2,4,6trinitrobenzene (TATB), and ammonium nitrate (AN) based materials. 4,[6][7][8][9] A variety of JWL EOS calibration methods have been developed previously based on data obtained in the CYLEX test configuration. The majority of these involve hydrodynamic simulations based on programmed burn (PB) calculations, where, for timing, the normal component of the detonation velocity is assumed constant, and where comparisons of PB simulations with experimental Cu wall expansion data are made at a discrete number of expansion volumes.…”

Reacting condensed phase explosives in direct contact

“…Concerning the determination of the upper limit, one can take advantage of thermodynamic understanding of the objective function [45]. For example, we can observe that in the limit of large ρ α we have T α < T β and therefore the function f Teq will be large and negative.…”

“…As before, the lower limits are deduced from the requirement that the density of each constituent must be positive. As for the determination of the upper limits, we have adopted the strategy proposed by Wilkinson et al [45], where the maximum density is obtained as the one for which the temperature equals zero at a pressure of 1.5 times the Von Neumann pressure [22]. As observed in Wilkinson et al [45], this somewhat arbitrary choice was found to eliminate any unphysical behaviour in the large density limit, while at the same time ensuring that the physical solution was never accidentally excluded from the search domain.…”