Observations on type II deflagration-to-detonation transitions

Type 11 DDT has been observed in low density charges of ultrafine PETN and RDX. The compressive burning regime that mediates the final stages of type I DDT has been shown to be absent in this mechanism. Convective burning controls the propagation of reaction throughout the column and detonation breaks out at some point along the column, The exact features of the detonation vary between PETN and RDX. The study described here gives new details on the pressure and temperature regimes that operate within the column during the build-up to detonation. Velocity measurements of the waves (in particular the detonation waves) found in these systems have been made. It has been shown that the detonation wave velocities are anomalous for materials at the initial pressing densities, with PETN having an enhanced detonation velocity following a type 11 DDT and RDX having a retarded detonation velocity.