Early experimental and theoretical investigations of solid propellant ignition seemed to indicate that ignition was caused by exothermic solid phase reactions stimulated at the exposed surface of a propellant by applied heat. Later experiments, in which nitrate ester and composite propellants were exposed to various gases at controlled high temperatures and pressures, showed that the ignition delay was influenced not only by the nature of the propellant, but by the quantity of oxidizer present in the external gas and the gas pressure Log-log plots of experimental ignition delay versus the gaseous oxidizer concentration exhibited a range of slopes from zero to minus two or more. These experiments indicated that the igniter gas plays a specific role in the ignition process, and that propellant ignition could- be due either to a reaction of propellant fuel molecules with the gaseous oxidant in a gas phase reaction, or to a heterogeneous surface reaction between oxygen and the solid phase fuel.
展开▼
