Determination of the transfer coefficient of natural turbulence occurring near the solid-propellant gasification zone. I. Two-phase model of the gasification zone

Abstract

A model for solid propellant gasification is proposed which contains a two-phase medium in an intermediate stage. The formation of the gas phase proceeds in two ways: chemical reactions result in gaseous products, which, in turn, initiate the formation of bubbles in which vapor forms from the liquid phase of the propellant. Gaseous products play an important role only in the very early stage of bubble development; their critical pressure is used to determine the minimum size of gas-phase nuclei. The bubble volume grows primarily by evaporation of the liquid phase. A kinetic equation for the bubble concentration and the necessary boundary conditions are formulated. Arguments are given suggesting that a temperature maximum cannot occur in the gasification zone and that natural turbulence can be generated by collapsing bubbles. The sound produced by solid propellant combustion is explained by the collapse of a huge number of microscopic bubbles. If the processes in the two-phase zone are neglected, the formulated system of equations is transformed into the Belyaev–Zel’dovich model equations.