Application of a Mixture Theory Model to the Explosive Dispersal of Solid Particles PDF Download
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Author: A. S. Geller
Publisher:
ISBN:
Category :
Languages : en
Pages : 60
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Book Description
Author: A. S. Geller
Publisher:
ISBN:
Category :
Languages : en
Pages : 60
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13
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This paper describes an experimental & numerical investigation of the rapid dispersal of inert solid particles due to the detonation of a heterogeneous explosive consisting of a packed bed of steel beads saturated with a liquid explosive. The interplay between the particle dynamics & the blast wave propagation was investigated experimentally as a function of the particle size & charge diameter with flash X-ray radiography & blast wave instrumentation. Difficulties in modelling the high-speed gas-solid flow are discussed, and a heuristic model for the equation of state for the solid flow is developed. This model is incorporated into a Eulerian two-phase fluid model and simulation results are presented. The results indicate the factors affecting the crossing of the particles through the shock front and the existence a particle size limit below which the particles cannot penetrate the shock for the range of charge sizes considered.
Author:
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Category : Power resources
Languages : en
Pages : 498
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Author: Bradley Marr
Publisher:
ISBN:
Category :
Languages : en
Pages :
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"The explosive dispersal of a heterogeneous medium, specifically a saturated or unsaturated particle bed, surrounding a high-explosive burster charge generates a complex multiphase flow. The developing cloud of particles and/or liquid droplets tend to have a non-uniform density distribution and can lead to the formation of jet-like structures. The tendency to form these jets in the dispersal of an unsaturated system has been seen to depend on the explosive loading and the material properties of the particles. Particles comprised of brittle ceramics or soft-ductile metals are more susceptible to forming jets, whereas particles with moderate hardness and high compressive strength are less prone to jet formation. The dominant mechanisms governing the generation of these jets has been a topic of debate amongst researchers.This thesis presents experimental and computational data supporting the theory that shock consolidation, dependent upon the characteristic material strengths of the medium, within a dispersed unsaturated particle bed is the governing mechanism responsible for the jetting phenomenon. After the formation of the consolidate, the dispersal events depend on the fracture and fragmentation of the particle shell. Mesoscale simulations using the EDEN hydrocode show that during the compaction and subsequent expansion of a layer of brittle ceramic particles, fractures emanate from the inner surface of the consolidate, propagate radially outward and bifurcate, consistent with the bimodal fragment size distribution observed in radiographic films obtained during experiments of the explosive dispersal of a silicon carbide particle bed. In contrast, mesoscale simulations of explosively dispersed ductile metal particles exhibit the typical shear and brittle fracture behaviour usually associated with the fragmentation of a metal casing, supporting the monomodal fragment size distribution observed in radiographic films from the dispersal of an aluminum particle bed. In addition to the main topic concerning the dispersal of an unsaturated particle bed comprised of a single particle type, two supplementary, closely-related problems are examined: (i) the explosive dispersal of unsaturated binary mixtures, and (ii) the explosive dispersal of saturated particle beds. The explosive dispersal of binary mixtures, containing both “jetting” and “non-jetting” particles, produces a particle cloud with features consistent with the superposition of the behaviour observed during the dispersal of the individual components. The effect of the particle bed configuration on the superposition behaviour is examined in the binary mixtures, by varying the volumetric ratio of the two types of particles and the charge loading. In saturated particle beds, the effects of heterogeneous cavitation at particle-liquid interfaces are examined through varying the morphology of the particles in the charge. Estimates of the initial velocities of the dispersed particle layers are also obtained from high-speed video records of the experimental tests. These results are compared with both the classical and porous Gurney models, and reasonable agreement is observed between the models and the experimental results, within the error estimates of the experimental velocities"--
Author:
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ISBN:
Category :
Languages : en
Pages : 30
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The Explosive dispersal of densely-packed metal particles in cylindrical RDX-based charges was studied numerically in support of experimental trials. Simulations were conducted using a reactive multiphase fluid dynamic code. Fundamental studies using a large-scale explosive were performed to show scaling phenomena while avoiding potential initiation and critical diameter effects. Spherical tungsten particles were applied in high metal mass fraction cylindrical and spherical charges in two configurations: a particle matrix uniformly embedded in a solid explosive versus an annular shell of particles surrounding a high-explosive core. The effect of particle number density was investigated by varying the nominal particle diameter from 27 to 120 microns while maintaining a constant metal mass fraction. Results were compared with steel particles to evaluate the influence of material density dispersal. Preliminary laboratory-scale simulations were performed using the anticipated experimental configuration for the High Explosives R & D facility at Eglin AFB trials. The effect of particle size and density were investigated, and information to assist in the experiments was obtained. Results were consistent with the fundamental study involving the large-scale explosives, particularly the shape of the cylindrical dispersed dense particle slug, and the relative performance of the large and small particles.
Author: M. J. Murphy
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
Multiphase flow phenomena are important in the characterization of many particle-loaded explosives. A numerical model of these flows must often be capable of accurately simulating both dense and dilute particle loadings and often the transition between the two limits. This presents severe numerical difficulties in that numerical approaches for packed particle beds often behave poorly for the dilute regime and the reverse is often true for methods developed for the dilute regime. This abstract compares two established numerical methods and presents improvements to them. The improved methods have enabled the development of a general purpose model that has been successfully applied to a wide range of problems including the energetic dispersal of solid particles.
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 700
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Book Description
Author: F. Zhang
Publisher: Springer Science & Business Media
ISBN: 3540884475
Category : Science
Languages : en
Pages : 407
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Book Description
The fourth of several volumes on solids in this series, the six extensive chapters here are more specifically concerned with detonation and shock compression waves in reactive heterogeneous media, including mixtures of solid, liquid and gas phases.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1128
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Author: Ralf Weinekötter
Publisher: Springer
ISBN: 9780792362296
Category : Science
Languages : en
Pages : 155
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Book Description
This book covers the theoretical and practical aspects of the mixing of solids and presents an overview as well as detailed know-how and experience. The book demonstrates the state of the art of mixing and segregation technology, quality control, design of mixers, design scale-up and engineering of complete processes. Includes checklists, criteria for choosing batch or continuous process, and practical examples of installed systems.
