On the neutralization of bacterial spores in post-detonation flows

Gottiparthi, Kalyana C.; Schulz, Joseph; Menon, Suresh

doi:10.1007/s00193-014-0504-9

Cited by 8 publications

(13 citation statements)

References 18 publications

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“…In the current two-phase model, the gas-phase is always computed using an Eulerian approach by solving the threedimensional Navier-Stokes equations for compressible, unsteady, reactive, multiphase flows [5,12,19]. For the particle phase, we employ both the EL [12,13,20] and the EE [10,17,18] methods.…”

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

“…Here, η k is the smallest fully resolved scale in the flow. The various acceleration, heat and mass transfer terms and models used here are discussed elsewhere [5,12,21], and not repeated for brevity.…”

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

“…The overall scheme is second order accurate in space and time. The Lagrangian dispersed phase governing equations are integrated using a 4th order Runge-Kutta time integration scheme [5]. Both gas and particle phases are simulated in parallel with the particles divided among the processors based on their physical location, and tracked by the corresponding processor.…”

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

“…The source terms from the Lagrangian dispersed phase are volume averaged, and both the Eulerian dispersed phase and the Lagrangian dispersed phase are coupled with the gas-phase equations via interphase source terms. The details of the complete source terms along with the validation of the EE, EL and EE-EL approaches for several canonical problems can be found elsewhere [5,22,21].…”

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

“…Such explosives are primarily designed to enhance the afterburn in the post-detonation flow field. Past studies of afterburn [1,2,3,4,5] have attempted to quantify the evolution of the blast wave and the mixing zone behind it, but these studies are mostly limited to explosives with a low volume fraction of solid particles, i.e., < 0.01. However, experimental and realistic high energy heterogeneous explosives contain a large number of particles with the range of volume fraction of particles between 0.01 to 0.65.…”

Section: Introductionmentioning

confidence: 99%

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Turbulent mixing and afterburn in post-detonation flow with dense particle clouds

Gottiparthi¹,

Menon²

2017

AIP Conference Proceedings

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Abstract. Augmentation of the impact of an explosive is routinely achieved by packing metal particles in the explosive charge. When detonated, the particles in the charge are ejected and dispersed. The ejecta influences the post-detonation combustion processes that bolster the blast wave and determines the total impact of the explosive. While the classical Eulerian-Lagrangian (EL) methods can accurately handle the post-detonation mixing zone in the dilute regime, the Eulerian-Eulerian (EE) method is preferred for the initial dense clustering. Here, we summarize the results obtained using both EL and EE methods as well as demonstrate a new hybrid EE-EL approach. The EL method, which is also developed to handle both dense and dilute flows using the discrete equation method, is used initially to study the dispersion of a relatively dense particle shell by blast waves. The results show distinct clustering of particles that later leads to the formation of jet-like structures as seen in experiments. Then, the hybrid EE-EL method is used to study the dispersion of dense clouds from explosives packed with aluminum (reactive) or steel (inert) particles. A transitioning criterion is used to smoothly transfer the initially dense Eulerian mass to Lagrangian particles when dilute. Results are presented to demonstrate that the approach is computationally efficient and accurate for certain ranges of particle sizes and loading. It is shown that mixing between the ambient and post-detonation products can be enhanced when particles are present in the flow. Furthermore, the afterburn of aluminum particles increases in the average gas-phase temperature by 100 K -200 K when compared to a case with non-reacting particles. More studies are still needed to establish a robust strategy for wider applications.

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Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

Section: Governing Equations and Numerical Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Turbulent mixing and afterburn in post-detonation flow with dense particle clouds

Gottiparthi¹,

Menon²

2017

AIP Conference Proceedings

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Experiments and Modeling for Biocidal Effects of Explosives

Henderson

Longbottom

Milne

et al. 2015

Propellants Explo Pyrotec

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] 1IntroductionBacterial spores such as Bacillus anthracis (anthrax) are potentially highly dangerous to human health, see for example Whitney et al. [1].E nergetic materials offer ap otential for rapid neutralization of such threats in operational environments since detonation and combustion can produce hot and in some cases corrosiveg ases, whichh ave ab iocidal effect.R ecent work by McCartt,G ates, and co-workers [2-4] and references cited therein has studied spore resistance to gasdynamic heating using aerosolized spores suspended in as hock tube and finds that significant neutralization occurs at temperatures above 650 K. Significant endospore damage is observed at temperatures above 750 K. Gottiparthi et al. [5] have built on the above data in numerical studies of neutralization of spores in post-detonation (using nitromethane as the explosive) free-field flows. There they considerasimple neutralization model where spores are neutralized if their temperature exceeds ac ritical temperature, which they take to be 670 K. Schulz et al. [6] have carried out systematic sensitivity studies basedo nt his modeling techniquea nd conclude that the residence time in the hot gases is ad ominant parameter.In our workw ec onsider detonation in an enclosed environment, where residence times are naturally much longer than in free field. The energetic material studied is Valimet H-2 aluminum powder,s hock dispersed by detonation of ac entral high explosive( HE) core. The experimental apparatus consists of two coupled closed chambers. The first chamber contains the energeticm aterial and is initially filled with Bacillust huringiensis Al Hakam (BtAH) sporesi n an aerosol. On detonation, the gasesa re free to vent into the second (exhaust) chamber, simulating venting from as tructure damaged by ab io-agent defeat strike. After the event, spores are captured from both chambers for postprocessing to determine the fraction remainingv iable. The primary diagnosticsa re the conditions in the detonation chamber and the resultingp ercentage of surviving spores.We also report the results of ar ange of numerical modeling studiesc arried out to aid the interpretation of these ex- Abstract:T his paper reports an experimental and modelling study of the biocidal effect of an energeticm ixture which is detonated in ac losed chamber containing an initial spore distribution. The resulting spore neutralization efficiency is recorded as af unctiono fm easuredd etonation and combustion performance. We also report the results of ar ange of numerical modelling studies carried out to aid the interpretation of these experiments and to guide future developments. We find that the current energetic mixture (aluminum powder whichi ss hock dispersed by detonation of ac entralh igh explosivec ore)g ives variable combustion efficiency.T he Al powder ignites on impact with the walls. In the modelling we matcht he recorded quasi-static pressures in each experiment and compare predicteds pore neutralization with measured values. Using ac riticals pore tempe...

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