Thrust Characterization of Very High Burning Rate Propellants

Abstract

Abstract : A series of closed bomb combustion tests were conducted on several very high burning rate (VHBR) propellants in which, in addition to the standard pressure measurements, the thrust produced by a burning propellant column was measured using a dynamic force gage located at the end of the propellant column. The results indicate that in several instances the total force imparted to the force gage substantially exceeded that due to the gas pressure alone. The difference is ascribed to the thrust or impulse resulting from very high apparent burning rates. In fact, an analysis of the data for two VHBR propellants indicates that effective burning rates from 100 to 300 m/s are required to produce the observed thrust levels. Such burning rates are not yet explainable by conventional combustion models. Additional physical processes such as convective flamespread or stress-induced surface fracture must be invoked to explain such high apparent burning rates.