Anomalies in Detonation Initiation of Liquid Explosives

Abstract

ATTENTION has recently been directed to the study of low velocity detonations (LVD) (refs. 1 and 2), which propagate at velocities only slightly supersonic with respect to the unreacted liquid and may be very easily initiated in some liquids. It is the purpose of this communication to show that both the shape and material of the container and the presence of a witness plate affect LVD initiation. Theories proposed for LVD (refs. 1–3) require that the container sound speed be greater than that of the liquid explosive. We have tested this prediction by using lead tubes with 1,2-difluoroaminopropane, a liquid known to sustain normal and low velocity detonations4. Because of the low sound velocity, we expected that weak initiating shocks would not yield LVD in lead though identical shocks would in steel. Unexpectedly, there was definite evidence of LVD propagation. The experiments were repeated and photographed with a high speed framing camera. The lead tubes used were 1.27 cm inner diameter × 0.635 cm wall × 10.4 cm long, and the shock source consisted of an exploding bridge-wire detonator, a small (∼ 1 g) RDX pellet, two pressed tetryl pellets (each 3.87 em diameter × 2.54 cm long; density ∼1.51 g/cc; weight ∼90 g), and a ‘Plexiglas’ attenuator (3.87 cm diameter × 30.5 cm long). The shock strength at the end of the attenuator was about 1 kbar compared with about 60 kbar required to initiate normal detonation.