Onset and development of convective burning in highly porous charges of ammonium perchlorate and its mixtures with aluminum

The onset and development of convective burning in the charges with a high porosity prepared from the finely dispersed ammonium perchlorate and its mixtures with aluminum ASD-4 is studied. The experiments were carried out in a constant volume bomb with the record of the pressure-time history and in the confinement with a slit, which makes it possible to perform simultaneously the photographic and piezometric recording of the process. Special attention is given to the mixtures with the increased aluminum content. The minimum lengths of samples are determined at which convective burning or explosion occur. The dependence of these lengths on the aluminum concentration in the mixture is determined. The possibility of convective burning and low-velocity detonation in ammonium perchlorate without the combustible additive is shown. It is established that the introduction of aluminum causes the ignition of the dispersed suspension behind the front of convective burning with the formation of the brightly glowing high-pressure zone (the secondary wave), which intensively expands in both sides from the place of origin. When the secondary wave overtakes the front of convective burning, the low-velocity detonation appears. The obtained results are of interest for explosion safety of the mixtures of ammonium perchlorate with aluminum and for designing generators of high-temperature suspensions with aluminum particles.