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Author:
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ISBN:
Category :
Languages : en
Pages : 13
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Book Description
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:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13
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Book Description
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: A. S. Geller
Publisher:
ISBN:
Category :
Languages : en
Pages : 60
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 30
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Book Description
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: 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: Frank Philip Bowden
Publisher: CUP Archive
ISBN: 9780521312332
Category : Science
Languages : en
Pages : 132
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Book Description
This book describes the research of Bowden, Yoffe and their collaborators on explosive initiation. What Bowden and Yoffe showed was that explosives are ignited almost invariably by thermal processes and though other processes have been identified their work still holds.
Author: Mark Douglas Kellenberger
Publisher:
ISBN:
Category :
Languages : en
Pages : 236
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Book Description
High-speed particle dispersion research is motivated by the energy release enhancement of explosives containing solid particles. In the initial explosive dispersal, a dense gas-solid flow can exist where the physics of phase interactions are not well understood. A dense particle flow is generated by the interaction of a shock wave with an initially stationary packed granular bed. The initial packed granular bed is produced by compressing loose aluminum oxide powder into a 6.35 mm thick wafer with a particle volume fraction of 0.48. The wafer is positioned inside the shock tube, uniformly filling the entire cross-section. This results in a clean experiment where no flow obstructing support structures are present. Through high-speed shadowgraph imaging and pressure measurements along the length of the channel, detailed information about the particle-shock interaction was obtained. Due to the limited strength of the Mach 2 incident shock wave, no transmitted shock wave is produced. The initial "solid-like" response of the particle wafer acceleration forms a series of compression waves that coalesce to form a shock wave. Breakup is initiated along the periphery of the wafer as the result of shear that forms due to the fixed boundary condition. Particle break-up starts at local failure sites that result in the formation of particle jets that extend ahead of the accelerating, largely intact, wafer core. In a circular tube the failure sites are uniformly distributed along the wafer circumference. In a square channel, the failure sites, and the subsequent particle jets, initially form at the corners due to the enhanced shear. The wafer breakup subsequently spreads to the edges forming a highly non-uniform particle cloud.
Author: S. Hernández
Publisher: WIT Press
ISBN: 1784663298
Category : Science
Languages : en
Pages : 251
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Book Description
Composed of papers presented at the 10th conference on Multiphase flow this book presents the latest research on the subject. The research included in this volume focuses on using synergies between experimental and computational techniques to gain a better understanding of all classes of multiphase and complex flow.
Author: S. Balachandar
Publisher: Cambridge University Press
ISBN: 1009184547
Category : Science
Languages : en
Pages : 676
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Book Description
Dispersed multiphase flows are frequently found in nature and have diverse geophysical, environmental, industrial, and energy applications. This book targets a beginning graduate student looking to learn about the physical processes that govern these flows, going from the fundamentals to the state of the art, with many exercises included.
Author: Gabi Ben-Dor
Publisher: Springer
ISBN: 331946213X
Category : Technology & Engineering
Languages : en
Pages : 746
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Book Description
These proceedings collect the papers presented at the 30th International Symposium on Shock Waves (ISSW30), which was held in Tel-Aviv Israel from July 19 to July 24, 2015. The Symposium was organized by Ortra Ltd. The ISSW30 focused on the state of knowledge of the following areas: Nozzle Flow, Supersonic and Hypersonic Flows with Shocks, Supersonic Jets, Chemical Kinetics, Chemical Reacting Flows, Detonation, Combustion, Ignition, Shock Wave Reflection and Interaction, Shock Wave Interaction with Obstacles, Shock Wave Interaction with Porous Media, Shock Wave Interaction with Granular Media, Shock Wave Interaction with Dusty Media, Plasma, Magnetohyrdrodynamics, Re-entry to Earth Atmosphere, Shock Waves in Rarefied Gases, Shock Waves in Condensed Matter (Solids and Liquids), Shock Waves in Dense Gases, Shock Wave Focusing, Richtmyer-Meshkov Instability, Shock Boundary Layer Interaction, Multiphase Flow, Blast Waves, Facilities, Flow Visualization, and Numerical Methods. The two volumes serve as a reference for the participants of the ISSW30 and anyone interested in these fields.
Author: Leonard Barolli
Publisher: Springer
ISBN: 3319656368
Category : Technology & Engineering
Languages : en
Pages : 635
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Book Description
The aim of this book is to provide the latest research findings, innovative research results, methods and development techniques from both theoretical and practical perspectives related to intelligent social networks and collaborative systems, intelligent networking systems, mobile collaborative systems, secure intelligent cloud systems, etc., and to reveal synergies among various paradigms in the multi-disciplinary field of intelligent collaborative systems. It presents the Proceedings of the 9th International Conference on Intelligent Networking and Collaborative Systems (INCoS-2017), held on August 24–26, 2017 in Toronto, Canada. With the rapid evolution of the Internet, we are currently experiencing a shift from the traditional sharing of information and applications as the main purpose of the Web to an emergent paradigm that puts people at the very centre of networks and exploits the value of people’s connections, relations and collaborations. Social networks are also pla ying a major role in the dynamics and structure of intelligent Web-based networking and collaborative systems. Virtual campuses, virtual communities and organizations effectively leverage intelligent networking and collaborative systems by tapping into a broad range of formal and informal electronic relations, such as business-to-business, peer-to-peer and many types of online collaborative learning interactions, including the emerging e-learning systems. This has resulted in entangled systems that need to be managed efficiently and autonomously. In addition, the latest and powerful technologies based on Grid and wireless infrastructure as well as Cloud computing are now greatly enhancing collaborative and networking applications, but are also facing new issues and challenges. The principal objective of the research and development community is to stimulate research that leads to the creation of responsive environments for networking and, in the longer-term, the developmen t of adaptive, secure, mobile, and intuitive intelligent systems for collaborative work and learning.
