Studies in the transition from deflagration to detonation in granular explosives—I. Experimental arrangement and behavior of explosives which fail to exhibit detonation

Abstract

The purpose of this paper is to describe apparatus and instrumentation whereby the sequence of events in confined burning of explosives can be followed. These events are pressure buildups, formation of a convective flame front, formation of a detonation front, or a pressure rupture of the confining tube. Furthermore, although a convective front has been observed in every reported case of transition from deflagration to detonation in granular explosives, we find that it also occurs (at about the same driving pressures and traveling at about the same velocity) in explosives unable to exhibit a transition in this apparatus. Data are presented from the confined burning of ammonium picrate at several compactions and of 95/5 TNT/Wax. Burning these relatively shock-insensitive explosives produces a mild pressurization of the confining tube which leads, after a period of instability, to the formation of a convective flame front and, eventually to tube rupture. The rapid pressure buildup necessary for a transition to detonation is absent. Confined burning of explosives which do exhibit transition is described in a companion paper.