Fluid mechanics of deflagration-to-detonation transition in porous explosives and propellants

The fluid mechanical processes which characterize a transition from deflagration to detonation in granular beds of solid propellant have not at present been sufficiently refined to allow accurate modeling of the phenomenon. In an attempt to improve this situation, this paper reports on the investigation of the basic mechanisms and consequences that arise from a set of assumptions for the governing and constitutive equations which take into account the two-phase nature of this problem. A qualitative description of the flow process is made, based on observations obtained from deflagration-to-detonation transition (DDT) experiments. From this, certain conclusions are reached as to the properties needed by propellants to exhibit a deflagration-todetonation transition. The numerical integration scheme itself is examined in detail in order to further understand the consequences of its use. Also, two scenarios for DDT are presented which exhibit characteristics similar to those derived from experimental evidence. Conclusions as to the direction of future research are made based on the results obtained from the work which led to these two basic mechanisms for DDT.