engleski

Numerical modelling of self-ignition of energetic materials

Thermal decomposition of energetic materials is accompanied by generation of heat, and under certain conditions may lead to the well-known phenomenon of the self-ignition (or thermal explosion). Therefore, it is of great concern of explosive community to predict whether or not a specimen of energetic material will ignite or not under given conditions (defined primarily by a specimen mass and shape, surrounding temperature, etc.). In order to describe the reactive heat conduction phenomena in an infinite slab, cylindrical, and spherical geometry of an explosive material, an own computer program, based on the thermal explosion theory and the finite difference method, was developed. The program is tested by the comparison of calculated times to ignition for some standard high explosives with times to ignition determined experimentally, as well as with times to ignitions calculated by some other authors. The results of calculations are also compared with the results of calculation according to an analytical solution of the heat balance equation derived by Frank-Kamenetskii. It was found out that not only values of the activation energy and pre-exponential factor, but also the kinetic model of thermal decomposition used in the calculation, have a crucial influence on the results of calculation. It was also shown that the Frank-Kamenetskii equation gives considerably lover values of the times to ignition, and higher values of the critical temperatures for explosives studied.

energetic materials; self-ignition; thermal explosion; numerical modeling

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