A New Approach for Modeling Pyrotechnic Particle Reactions Using Hot-Spot Calculations

摘要

Normally pyrotechnics compositions consist of fuel and oxidizer particle mixtures. The burning behavior is controlled by different known factors. The most important physical properties are fuel and oxidizer concentration, particle size, particle distribution, and resulting heat of reaction, melting, evaporation and decomposition of the particles. The main physical processes which take place are the heat and mass transfer and the reaction kinetics. Since now only few approaches exist to model the influence of particle distribution and particle size on the burning behavior. Based on a hot-spot model in combination with thermodynamic equilibrium calculations a new simple approach with reduced numerical expense is presented which is mainly suitable to granular reactions with low gas production like thermites. The model in parallel solves the heat and mass transfer equation under consideration of a chemical reaction. In this paper the model is applied to different particle size ratios of fuel and oxidizer particles (1:1, 2:1, and 3:1) at random particle distributions. The influence on the propagation rate will be discussed. In a later investigation the results will be compared to experimental results of progression rates from Al/CuO-thermite mixtures with aluminum contents from 8% to 70%. In this instance it is an extension of [1]. The theory, the experimental setup and the data analyzing were there discussed in detail also the determination of the needed parameters for the hot-spot model.