A Chemically Specific Burning Rate Predictor Model for Energetic Materials

Abstract

The application of complex networks of elementary chemical reactions to the gas phase of burning energetic materials has increased markedly over the last decade. The exquisite complexity of these gas-phase reaction networks, coupled with available high-rigor treatments of transport, is not matched by an equivalent level of sophistication in descriptions of the condensed-phase and interfacial phenomena. Owing to the vastly more complicated, many-body nature of the condensed phase, this condition is not likely to be relieved soon. In response to these difficulties, a new semi-empirical approach to burning-rate calculation has been developed and applied to frozen ozone, cyclotrimethylenetrinitramine (RDX), and nitroglycerine. The new approach hypothesizes a single overall reaction linking the unreacted material to the net products of condensed-phase decomposition and characterizes their rate of formation according to an empirically derived pyrolysis law. These condensed-phase products become the reactants for the gas phase, which are treated in full elementary-reaction detail. Using this new semi-empirical model, a methodology for computing the relative effects of several additives on the burning rate of nitroglycerine is developed and demonstrated. Hopefully this approach will enable more rapid progress in modeling multi-ingTedient propellants than did previous approaches attempting to model the condensed-phase processes in detail.