Errors in Using Balance Relations in the Theory of Combustion of Condensed Systems

Abstract

Due to the total lack of reliable experimental data on the kinetics of solid-phase transformations at high temperatures, adequate estimates of the ignition and combustion characteristics of real energetic materials are currently unavailable. In combustion theory, balance relations in the form of ignition criteria and in the form of the principle of equivalence of the burning rate increase under the action of a radiant flux to the corresponding increase in the initial temperature are used in most cases without sufficient theoretical justification, what can lead to incorrect results. Numerical simulation of the ignition and combustion of model energetic materials can provide a basis for determining the conditions for the correct use of balance relations. In this work, using a model of unsteady combustion of melting energetic materials, ignition and combustion under the action of a radiant flux have been studied numerically and the fitting coefficients in the balance relations have been obtained. It has been shown that the values of these coefficients depend on the kinetic parameters of solid-phase transformations and the intensity of the external heating source. It is concluded that it is necessary to continue the theoretical research aimed at developing valid approaches to determine the parameters of global reactions in the condensed phase using data on the delay of ignition by heat flux and to determine the correct fitting coefficients when using the equivalence principle.