The influence of aluminum particle dispersion on the burning rate of metallized solid propellants

The paper presents a physical-mathematical model for combustion of a mixed solid propellant based on ammonium perchlorate with addition of aluminum (Al) particles. The thermal effect of the condensed phase decomposition, convection, diffusion, the gas phase exothermic reaction, Al particles heating up and burning in the gas flow, the combustion products flow, and the particle velocity lag compared with that of gas were taken into consideration. The study also focused on how the size and mass fraction of Al particles leaving the burning surface affect the burning rate. The size effect of Al particles leaving the burning surface on the gas parameters distribution and linear burning rate was studied. It was shown that the Al particle dispersion in the gas phase had a significant influence on the distribution of parameters in the layer above the burning surface and on the burning rate. Thus, to calculate the linear burning rate of a metallized solid propellant, it is important to know not only the kinetics of chemical reactions in the gas phase, but also the dispersion of metal particles leaving the burning surface of the condensed phase.