Mathematical Modelling on Extinction of Metallized Composite Solid Propellant Under a Sudden Drop in Pressure

Abstract

This paper presents a physico-mathematical combustion model of the metallized composite solid propellant (MCSP), which takes into account the chemical reactions in the condensed and gas phases. The model describes convection and diffusion of the propellant components in the two-phase flow over the fuel surface and combustion of the aluminium particles emitted from the fuel. The constructed model provides the opportunity to calculate the fuel combustion rate under the constant and variable pressure. The obtained calculation results of the MCSP combustion rate using the model are in good agreement with the known experimental data. The manuscript also provides data on the modelling of the MCSP extinction under the sudden pressure change. According to the conducted numerical simulations, the value of the pressure drop, leading to the fuel extinction, depends on the mass fraction of the aluminium powder in the fuel composition and its dispersion. With an increase in the mass fraction of the aluminium powder and/or a decrease in the size of the aluminium particles emitting from the fuel surface, the extinction process occurs at a greater value and under a higher rate of the pressure drop. The numerical simulation has also shown that the addition of the aluminium powder to the composition of the propellant increases the combustion stability under the sudden drop in pressure over the combustion surface.