A CRITICAL ANALYSIS OF ARC IMAGE IGNITION OF SOLID PROPELLANTS
PRINCETON UNIV NJ DEPT OF AEROSPACE AND MECHANICAL SCIENCES
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The arc image furnace is used widely for evaluating solid propellant ignition characteristics, but the applicability of such data to rocket motors is questionable. In arc image testing, radiation replaces the normal conductive and convective heating modes that exist in rocket motor ignition radiation interacts with the propellant in a basically different way. Thus, for example, because radiation is absorbed in depth, the ignition delay is sensitive to propellant opacity. In addition, radiation can cause subsurface disruption of the propellant. A physical model is proposed in which incident radiation penetrates the propellant and is absorbed, causing thermal and photochemical decomposition and a temperature increase. Oxidative reactions start either in the gaseous boundary layer or on the surface and, by thermochemical action, lead to a flame. The system of differential equations for this complete model is complicated and has not been solved. However, an equivalent model of simpler character is solved, and an equation is produced for the ignition time delay as a function of radiation intensity, pressure, and physico-chemical properties. The qualitative behavior of experimental radiative ignition data reported by Beyer and Fishman and by Bastress is explained by this theory.
- Combustion and Ignition
- Solid Rocket Propellants