Estimating ignition delay times of nitroglycerin: A chemical kinetic modeling study

Nitroglycerin (NG) is commonly used as an ingredient in propellant formulations. In this study, a first automatically generated detailed kinetic model of this energetic material has been developed. The construction of this model was made possible by performing computations with the open source software package Reaction Mechanism Generator (RMG). To enable a faster convergence, significant intermediate species of NG decomposition and optimized operating conditions were indicated in the RMG input parameters. Thermochemical data related to significant decomposition species were derived from ab initio calculations at the DFT B3LYP/6-31 G(d,p) level of theory. To validate the RMG-built mechanism, simulations were performed with CHEMKIN-Pro. Computed species profiles from simulations were compared with flash pyrolysis measurements from the literature. Sensitivity analyses were performed on species mole fraction, and the most significant elementary reactions were identified. Some rate constant parameters were adjusted within the reaction rate uncertainty to improve the predictability of the model. Ignition delay times were computed for NG, and consistent trends were obtained when compared against to calculations for RDX and TNT using referenced model available in the literature. Although experimental data are scarce, this automated kinetic generation approach, applied to energetic materials, is to be highly promising.