On the systematics of particle velocity histories in the shock-to-detonation transition regime

Abstract

Analysis of recent high quality, in-material gauge results from two cyclotetramethylene tetranitramine based explosives and one triamino trinitrobenzene based explosive has shown a number of significant correlations. These include the strong monotonic relationship between the local shock strength and the time to peak particle velocity along each particle path, and the simple scaling of velocity histories along the particle path that exists at a common local shock strength from shots with different initial conditions. Even shocks that have radically different evolutions, such as double shocks or those arising from thin pulses, show the same correlations once the catch-up of the second shock or rarefaction has occurred. From the correlations the strongest relationship is demonstrated to occur between the reaction and the local shock strength. Hence reaction, at least to first order, is a function of shock strength and time along the particle path, and is independent of local flow variables behind the shock such as pressure and temperature. Arguments are presented to suggest that shock entropy is the most likely measure of the shock strength which controls the reaction.