Observation of deflagration wave in energetic materials using reactive molecular dynamics

K Joshi and S Chaudhuri, COMBUSTION AND FLAME, 184, 20-29 (2017).

DOI: 10.1016/j.combustflame.2017.05.009

Currently, there is no universal atomistic approach for simulating the combustion chemistry of a moving deflagration wave in condensed phase energetic materials. A reactive molecular dynamics based approach is used to identify the thermochemical events behind the formation and the propagation of a thermally initiated deflagration wave in the condensed phase RDX. The reactive molecular dynamics trajectory is mapped onto Eulerian control volumes to calculate the mass, energy and chemical flux across such deflagration front. A transition from ignition to a self- sustaining deflagration front occurs when the mass transport at the front exceeds the thermal transport in the course of propagation. Upon the formation of a self-sustaining deflagration front, a sudden rise in temperature at the front is observed accompanied by increase in the local density of the unreacted solid ahead of the front. The observed energy flux across the propagating deflagration front agrees well with the previously reported heat of explosion predictions. The deflagration front chemistry of RDX is dominated by the intermolecular and the intramolecular H-transfer reactions and subsequent formation of short- lived heavier polyradicals similar to the non-volatile residue reported in the literature. Chemical analysis indicates that the deflagration front is composed of a reactive chemical mixture of molten RDX, polyradicals and lighter intermediate radicals with intact triazine rings. (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

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