Combustion and Flame, Vol.219, 225-241, 2020
Evaluation of reaction kinetics models for meso-scale simulations of hotspot initiation and growth in HMX
Meso-scale modeling of heterogeneous energetic materials requires accurate description of the chemical reaction model that governs the decomposition of solid energetic crystals to gaseous products. For HMX, various 1-step and multi-step Arrhenius based chemical kinetic models are available; these chemical kinetics models for HMX have been calibrated against macro-scale experimental data under different ranges of pressure and temperature conditions, which may lie outside the ranges that arise during void collapse. Therefore, depending on the reaction model, the predicted meso-scale hotspot initiation and growth behavior can vary. Here, we examine the effects of five global HMX reaction kinetics models on predictions of void collapse induced hotspots, viz. the Henson-Smilowitz 1-step (HS1), Menikoff 1-step (M1), TarverNichols 3-step (TN3), Henson-Smilowitz 9-step (HS9) and a 7-step extended Brill-Yetter model (BYS7). Variations in the hotspot behavior predicted using the different models are observed to be significant. A detailed examination of the individual reaction mechanisms of each of these global chemistry models is undertaken to provide insights and understanding of the reaction steps that lead to the differences in the predicted hotspot behavior. For the temperature regime relevant to the void collapse generated hotspots, the differences in the hotspot behavior are attributed to the orders of magnitude variations in the reaction rates that govern the maximum energy release during HMX decomposition. The paper shows that the issue of a suitable kinetics model, even for the commonly used HMX material, remains unsettled. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.