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One and two dimensional numerical simulation of deflagration to detonation transition phenomenon in solid energetic materials

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2010
Narin, Bekir
In munitions technologies, hazard investigations for explosive (or more generally energetic material) including systems is a very important issue to achieve insensitivity. Determining the response of energetic materials to different types of mechanical or thermal threats has vital importance to achieve an effective and safe munitions design and since 1970’s, lots of studies have been performed in this research field to simulate the dynamic response of energetic materials under some circumstances. The testing for hazard investigations is a very expensive and dangerous topic in munitions design studies. Therefore, especially in conceptual design phase, the numerical simulation tools for hazard investigations has been used by ballistic researchers since 1970s. The main modeling approach in such simulation tools is the numerical simulation of deflagration-todetonation transition (DDT) phenomenon. By this motivation, in this thesis study, the numerical simulation of DDT phenomenon in solid energetic materials which occurs under some mechanical effects is performed. One dimensional and two dimensional solvers are developed by using some well-known models defined in open literature for HMX (C4 H8 N8 O8) with 73 % particle load which is a typical granular, energetic, solid, explosive ingredient. These models include the two-phase conservation equations coupled with the combustion, interphase drag interaction, interphase heat transfer interaction and compaction source terms. In the developed solvers, the governing partial differential equation (PDE) system is solved by employing high-order central differences for time and spatial integration. The two-dimensional solver is developed by extending the complete two-phase model of the one-dimensional solver without any reductions in momentum and energy conservation equations. In one dimensional calculations, compaction, ignition, deflagration and transition to detonation characteristics are investigated and, a good agreement is achieved with the open literature. In two dimensional calculations, effect of blunt and sharp-nosed projectile impact situations on compaction and ignition characteristics of a typical explosive bed is investigated. A minimum impact velocity under which ignition in the domain fails is sought. Then the developed solver is tested with a special wave-shaper problem and the results are in a good agreement with those of a commercial software.