Post-Detonation Energy Release From TNT-Aluminum Explosives

Zhang, Fan; Anderson, John G.; Yoshinaka, Akio

doi:10.1063/1.2833268

Cited by 8 publications

(5 citation statements)

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“…TNT explosion performance has been experimentally studied in both free-field configurations (unconfined) and closed vessels (full confinement) (Ornellas, 1982;Zhang, et al, 2007;Kuhl et al, 1998;Wolanski et al, 2000). Other researchers have gained insight into the afterburning phenomena using numerical (Kuhl et al, 1998;Kuhl.…”

Section: A Af Ft Te Er Rb Bu Ur Rn Ni In Ng G O Of F T Tn Nt Tmentioning

confidence: 99%

Afterburning Aspects in an Internal TNT Explosion

Edri

Feldgun

Karinski

et al. 2013

International Journal of Protective Structures

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The afterburning is a complex chemical process which stems from the reaction of the detonation products with the oxygen in the air when appropriate conditions exist. TNT is a very fuel-rich explosive as indicated by the large negative oxygen balance value of −74%. It means that there is not enough oxygen in its initial chemical compound and extra oxygen is needed to make the afterburning energy release possible. This article describes in details the calculation process for evaluating the amount of energy release in a confined TNT explosion. Moreover, partial afterburning energy release is also calculated for cases of oxygen deficiency. Commonly, numerical simulations take into account only the detonation energy in blast pressure analysis and it is responsible for under prediction of blast pressures in a confined explosion. Accounting for the afterburning energy as well considerably improves the predictions and yields pressures that are in good correspondence with measured data. The calculation time however increases by an order of magnitude. An afterburning coefficient was defined as the relation between the total energy released and the detonation energy. This coefficient was found useful for correcting numerical simulation results of TNT confined explosion which take into account only the detonation energy. This correction can be achieved by multiplying the pressure-time history with the afterburning coefficient. In addition, an analytic method, based on thermodynamic rules, was developed for calculating the gas pressure resulted by TNT confined explosion. This unique method takes into account the variation of the total energy released and the heat capacity ratio depending on the ratio between the charge weight divided by the confined air volume. The gas pressure obtained using this method was shown to be in good agreement with experimental results that are published in the literature.

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Section: A Af Ft Te Er Rb Bu Ur Rn Ni In Ng G O Of F T Tn Nt Tmentioning

confidence: 99%

Afterburning Aspects in an Internal TNT Explosion

Edri

Feldgun

Karinski

et al. 2013

International Journal of Protective Structures

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Section: a Af Ft Te Er Rb Bu Ur Rn Ni In Ng G O Of F T Tn Nt Tmentioning

confidence: 99%

On Blast Pressure Analysis Due to a Partially Confined Explosion: III. Afterburning Effect

Edri

Feldgun

Karinski

et al. 2012

International Journal of Protective Structures

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This paper aims at extending our understanding with regard to some characteristics of an interior explosion within a room with limited venting. An interior explosion may be the result of an ammunition storage explosion, or an explosive charge as part of a terrorist action or a warhead explosion that follows its penetration into a closed space in a military action. Full scale experiments have been performed with a TNT charge detonated at the center of a single room sized space with rigid boundaries. The room has a limited size opening for venting at the ceiling. Numerical simulations of the problem have been performed using AUTODYN Ver. 12.1 and compared with the experimental measurements. Some deviations between the measured pressure and the predicted pressure motivated the present study in an attempt to study the effect of the additional energy released due to the burning of the detonation products reacting with the surrounding oxygen. The study that is described in this paper enhanced our understanding. Incorporation of this effect considerably improved the predictions. The present study clarified when, how and to what extent the afterburning should be introduced in the analysis.

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“…The study of dispersion and ignition of aluminum particles by explosive blast waves and their interaction with hydrodynamic instabilities is still in its infancy, and requires more elaborate studies -this paper aims to provide some useful insights along these lines. These studies have applications to explosive dispersal of reactive metal particles -also known as Shock-Dispersed Fuel (SDF) charges [9,10] -where hydrodynamic instabilities can play a significant role in the amount of late time mixing and afterburn. Insights on the physics of particle dispersion due to their interaction with hydrodynamic instabilities can be directly applied for investigations of SDF charges.…”

Section: Introductionmentioning

confidence: 99%

“…Recent experimental studies of Shock-Dispersed Fuel (SDF) charges [9,10], i.e., charges of a high explosive surrounded with a shell of aluminum particles, have shown that significant amounts of afterburn, both of the detonation products as well as the aluminum, results in increased impulse. If ambient particles are too small and/or Downloaded by [University of South Florida] at 08: 37 19 November 2014 Combustion Theory and Modelling 585 light, the leading blast wave may rapidly set them into motion and they may never interact with the contact surface.…”

Section: Introductionmentioning

confidence: 99%

On turbulent chemical explosions into dilute aluminum particle clouds

Balakrishnan

Menon

2010

Combustion Theory and Modelling

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We use a hybrid two-phase numerical methodology to investigate the flow-field subsequent to the detonation of a spherical charge of TNT with an ambient distribution of a dilute cloud of aluminum particles. Rayleigh-Taylor instability ensues on the contact surface that separates the inner detonation products and the outer shock-compressed air due to interphase interaction, which grows in time and results in a mixing layer where the detonation products afterburn with the air. At early times, the ambient particles are completely engulfed into the detonation products, where they pick up heat and ignite, pick up momentum and disperse. Subsequently, as they disperse radially outwards, they interact with the temporally growing Rayleigh-Taylor structures, and the vortex rings around the hydrodynamic structures results in the clustering of the particles by also introducing local transverse dispersion. Then the particles leave the mixing layer and quench, yet preserve their hydrodynamic 'footprint' even until much later; due to this clustering, preferential heating and combustion of particles is observed. With a higher initial mass loading in the ambient cloud, larger clusters are observed due to stronger/larger hydrodynamic structures in the mixing layer -a direct consequence of more particles available to perturb the contact surface initially. With a larger particle size in the initial cloud, clustering is not observed, but when the initial cloud is wider, fewer and degenerate clusters are observed. We identify five different phases in the dispersion of the particles: (1) engulfment phase; (2) hydrodynamic instability-interaction phase;(3) first vortex-free dispersion phase; (4) reshock phase; and (5) second vortex-free dispersion phase. Finally, a theoretical Buoyancy-Drag model is used to predict the growth pattern of the 'bubbles' and is in agreement with the simulation results. Overall, this study has provided some useful insights on the post-detonation explosive dispersal of dilute aluminum particle clouds.

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Post-Detonation Energy Release From TNT-Aluminum Explosives

Cited by 8 publications

References 0 publications

Afterburning Aspects in an Internal TNT Explosion

Afterburning Aspects in an Internal TNT Explosion

On Blast Pressure Analysis Due to a Partially Confined Explosion: III. Afterburning Effect

On turbulent chemical explosions into dilute aluminum particle clouds

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