SIMPLIFIED MODELING OF TRANSITION TO DETONATION IN POROUS ENERGETIC MATERIALS

A simplified model that can predict the transitions from compaction to detonation and shock to detonation is given with the aim of describin g experiments in beds of porous HMX. In the case of compaction to deto nation, the energy of early impact generates a slowly moving, convecti ve-reactive deflagration that expands near the piston face and evolves in a manner that is characteristic of confined deflagration to detona tion transition. A single-phase state variable theory is adopted in co ntrast to a two-phase axiomatic mixture theory. The ability of the por ous material to compact is treated as an endothermic process. Reaction is treated as an exothermic process. The algebraic (Rankine-Hugoniot) steady wave analysis is given for inert compaction waves and steady d etonation waves in a piston supported configuration, typical of the ex periments carried out in porous HMX. A structure analysis of the stead y compaction wave is given. Numerical simulations of deflagration to d etonation are carried out for parameters that describe an HMX-like mat erial and compared with the experiments. The simple model predicts the high density plug that is observed in the experiments and suggests th at the leading front of the plug is a secondary compaction wave. A sho ck to detonation transition is also numerically simulated.