Burning to detonation transition in porous beds of a high-energy propellant

The deflagration-to-detonation transition process for high-energy propellants - A review

“…Finally, the observation, for this low- Dependence of f on initial compaction for various propellant particle sizes and shapes. 44 confinement system, that there is a minimum permeability at which the propellant was most susceptible is in agreement with earlier observations made with crystalline explosives under high-confinement conditions. 34 " 36 A cross-linked double-base (XLDB) propellant has been studied at high-confinement conditions by Bernecker et al 44 ; the ignition system used there can also be classified as a strong ignitor.…”

“…The gas pressure, which results from some CC and some burning along the lateral surfaces of the radially compacted charge (at least in the case of the propellant), produces compressive wavelets that initiate compressive burning. If the hot spots are readily formed and grow sufficiently rapidly at low pressure levels, then a transition to detonation can occur because the pressure growth from hot-spot reaction is very localized 44 and it is the inertial aspects of the confinement that then are important. From these mechanistic considerations, it was evident that the extent of CC and the shock reactivity and sensitivity of a propellant in the porous state are important processes needing to be evaluated in order to quantify our knowledge of the fundamentals affecting the susceptibility of various propellant formulations to DDT.…”

“…44 The pressure in the ignition region increased slowly and linearly with time. Accelerating pressure buildup (a necessary but not sufficient condition for DDT) was observed to occur shortly before (both in time and distance) the onset of detonation.…”

“…Having demonstrated that CC is minimal for the very compressible XLDB propellant, the data from Ref. 44, as shown in Fig. 3, for the shreds and granules were re-evaluated.…”

“…Considering that tetryl (a Mode II material) exhibited little CC, 50 it was of interest to reexamine the XLDB propellant data 44 and conduct additional experiments to evaluate the extent of CC using the x-ray displacement method of Ref. 50.…”