A new mechanism for deflagration-to-detonation in porous granular explosives

Gifford, M. J.; Luebcke, P. E.; Field, J. E.

doi:10.1063/1.370957

Cited by 19 publications

(9 citation statements)

References 14 publications

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“…It has been observed that there is a considerable amount of variability exhibited between different events or runs of the same experiment. For example consider the experiments by Luebcke et al 14 and by Gifford et al, 40 where a column of low density ultrafine PETN powder ͑particle size of approximately 1 m͒ at 29% TMD was ignited using a thermal initiator. Streak records of the event transients of each experiment were taken.…”

Section: Variation Observed Within Experimentsmentioning

confidence: 99%

Modeling deflagration-to-detonation transition in granular explosive pentaerythritol tetranitrate

Sáenz

Stewart

2008

Journal of Applied Physics

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Based on an approach suggested by Stewart et al. ͓Phys. Fluids 6, 2515 ͑1994͔͒ we develop a model to simulate deflagration-to-detonation transition ͑DDT͒ in pentaerythritol tetranitrate ͑PETN͒ powders. The model uses a continuum mechanics formulation of conservation laws for a mixture of solid reactants and gas products, written in terms of mixture quantities plus two independent variables used to account for exothermic conversion of solid reactants into gas products, and compaction associated with pore collapse and grain rearrangement. We propose a simple empirical dependence of the reaction rate on the initial bed compaction that allows us to calibrate the model for a wide range of initial conditions. For the solid reactants we use a wide-ranging equation of state ͑EOS͒ developed by Davis and co-workers in a series of papers

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Section: Variation Observed Within Experimentsmentioning

confidence: 99%

Modeling deflagration-to-detonation transition in granular explosive pentaerythritol tetranitrate

Sáenz

Stewart

2008

Journal of Applied Physics

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“…125 In laboratory based studies, high speed streak photography is favoured owing to the extra spatial detail, the continuous nature of the record and their flexibility. 126 More novel approaches, based on other optical techniques, 127,128 have also been used. To use these diagnostics, experiments often have to be conducted with dimensionally constrained explosive charges rather than the full three dimensions of an actual device.…”

Section: Ddt and Sdt Studiesmentioning

confidence: 99%

Crystal sensitivities of energetic materials

Walley¹,

Field²,

Greenaway³

2006

Materials Science and Technology

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116

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Organic and inorganic explosives were first developed and put into service in the 19th century, before there was much understanding of how the energy release mechanisms differed from those of the long established gunpowder. Theoretical advances in the understanding of shock waves combined with improvements in photographic and electronic techniques led to the hypothesis that a detonation is a shock wave maintained by the rapid release of chemical energy. Studies of accidental ignitions/initiations showed that explosive events can occur even when the energy input is much less than that required to heat the bulk explosive to the deflagration temperature. Hence, the highly fruitful idea of the localised hot spot was conceived. Apart from electrical stimuli, the main hot spot mechanisms are currently accepted as being adiabatic asymmetric collapse of gas spaces (producing gas heating, jetting, viscoplastic work) and the rubbing together of surfaces as in friction or adiabatic shear. Initiation mechanisms are also connected with the anisotropy of plasticity and fracture in explosive crystals. Decomposition of molecules can take place as they are forced past each other in a deforming crystal. There is, however, still much to discover about reaction pathways. Novel optical and electron microscopy techniques have given a great deal of new and precise information about displacements and failure mechanisms when explosive crystals are bonded together using polymers. The deflagration-detonation transition (DDT) has been extensively studied in model one-and two-dimensional systems.

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“…The pressure behind the plug causes a shock wave to be released through it and into the compacted material ahead of it which eventually evolves into a detonation wave. Type I DDT has been observed and studied in coarse (~180 µm particle) PETN [36].…”

Section: Petn Initiation: Deflagration To Detonation (Ddt)mentioning

confidence: 99%

PETN Exploding Bridgewire (EBW) Detonators: A Review

Neal

2020

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Exploding bridgewire (EBW) detonators have been used in weapon systems since the 1940s but there is huge debate surrounding how energy is transferred throughout the EBW firing system and the mechanism by which the exploding wire leads explosive detonation. This report summarizes the underpinning technologies and physical processes that are currently understood and reviews the various efforts to quantify the mechanism by which the PETN is initiated. The behavior of the firing system is very well understood and predictable. The energy delivered to the wire has been empirically modelled but further investigation is required to understand the role of material heterogeneities and their effect on initiation. The energy delivered by the exploding wire has been quantified in many studies but it is not possible to correlate these to a particular design or firing regime and thus definitive conclusions are impossible. The energy absorbed by the PETN is also not well understood. Therefore, the initiation mechanism within the PETN EBWs has not been determined for EBW detonators. There is strong evidence that a shock-todetonation (SDT) mechanism is not the sole cause of initiation. There is insufficient understanding of how electrical sparks transmit energy to PETN to make any judgement regarding the role gas ionization plays. Deflagration-to-detonation (DDT) seems like the most likely candidate for initiation but there is still a great lack of evidence for the presence of this mechanism.

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A new mechanism for deflagration-to-detonation in porous granular explosives

Abstract: The channel effect: Coupling of the detonation and the precursor shock wave by precompression of the explosive

Cited by 19 publications

References 14 publications

Modeling deflagration-to-detonation transition in granular explosive pentaerythritol tetranitrate

Modeling deflagration-to-detonation transition in granular explosive pentaerythritol tetranitrate

Crystal sensitivities of energetic materials

PETN Exploding Bridgewire (EBW) Detonators: A Review

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