Experimental study on ignition reaction evolution of pressed PBX-B in long thick wall cylinder confinement

In order to explore the possibility of deflagration to detonation transition (DDT) of pressed HMX-based PBX inside long thick wall steel tube initiated by ignition composition, a new experiment apparatus was designed based on traditional DDT tube, in which strength at specific locations enhanced, and multichannel PDV probes and high speed photography were used to diagnose the expansion process and rupture characteristics of tube wall. Compared with the results initiated by detonator in the same explosives and confinement, the reaction durations of detonation and ignition differed by orders of magnitude; the pressure evolution measured by tube wall velocities, and the propagation process of tube wall movement were significantly different in two reaction. Analysis shows that the convective flow of reaction products along the seam between tube wall and explosives, high temperature and pressure, dominated the reaction evolution of PBX-B initiated by ignition composition under strong confinement, and appeared as laminar burning on explosive surface and structural response of confinement. There is no reaction activated in explosive bulk by the ramp wave caused by upper stream non shock initiation reaction, least of all DDT.