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Author: Tariq Dennis Aslam
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
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Book Description
A detonation is a combustion-driven shock wave. Typically, a detonation will consist of an inert shock followed by a region of chemical reaction referred to as the reaction zone. Detonations have a wide variety of engineering applications, from obvious military uses to explosive welding, hard rock mining, and materials processing. Detonations can occur in a variety of materials, including gases (such as premixed hydrogen and oxygen), liquids, and solid explosives. Of particular interest in detonation problems is the motion of the detonation shock. Changes to the reaction zone may cause large variations in the strength and speed of the detonation front, so it can not be ignored in modeling detonations. For typical explosives, the reaction zone may be thousands of times smaller than the engineering scale. This multi-scaled nature of detonation can pose problems when trying to predict the motion of the detonation front. Detonation shock dynamics is an asymptotic theory whose key result is an intrinsic partial differential equation for the dynamics of the detonation shock front. It will be demonstrated that the theory can predict several aspects of unsteady multi-dimensional detonations accurately. Three intrinsic relations will be examined and compared with direct numerical simulations. Their relevance to modeling detonation dynamics will also be given. Numerical methods, based on level-set ideas, will be given for propagating multi-dimensional detonation fronts in arbitrarily complex geometries.
Author: Tariq Dennis Aslam
Publisher:
ISBN:
Category :
Languages : en
Pages : 210
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Book Description
A detonation is a combustion-driven shock wave. Typically, a detonation will consist of an inert shock followed by a region of chemical reaction referred to as the reaction zone. Detonations have a wide variety of engineering applications, from obvious military uses to explosive welding, hard rock mining, and materials processing. Detonations can occur in a variety of materials, including gases (such as premixed hydrogen and oxygen), liquids, and solid explosives. Of particular interest in detonation problems is the motion of the detonation shock. Changes to the reaction zone may cause large variations in the strength and speed of the detonation front, so it can not be ignored in modeling detonations. For typical explosives, the reaction zone may be thousands of times smaller than the engineering scale. This multi-scaled nature of detonation can pose problems when trying to predict the motion of the detonation front. Detonation shock dynamics is an asymptotic theory whose key result is an intrinsic partial differential equation for the dynamics of the detonation shock front. It will be demonstrated that the theory can predict several aspects of unsteady multi-dimensional detonations accurately. Three intrinsic relations will be examined and compared with direct numerical simulations. Their relevance to modeling detonation dynamics will also be given. Numerical methods, based on level-set ideas, will be given for propagating multi-dimensional detonation fronts in arbitrarily complex geometries.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 308
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Book Description
This document is a final report that summarizes the research findings and research activities supported by the subcontract DOE-LANL-9-XG8-3931P-1 between the University of Illinois (D.S. Stewart Principal Investigator) and the University of California (Los Alamos National Laboratory, M-Division). The main focus of the work has been on investigations of Detonation Shock Dynamics. A second emphasis has been on modeling compaction of energetic materials and deflagration to detonation in those materials. The work has led to a number of extensions of the theory of Detonation Shock Dynamics (DSD) and its application as an engineering design method for high explosive systems. The work also enhanced the hydrocode capabilities of researchers in M-Division by modifications to CAVEAT, an existing Los Alamos hydrocode. Linear stability studies of detonation flows were carried out for the purpose of code verification. This work also broadened the existing theory for detonation. The work in this contract has led to the development of one-phase models for dynamic compaction of porous energetic materials and laid the groundwork for subsequent studies. Some work that modeled the discrete heterogeneous behavior of propellant beds was also performed. The contract supported the efforts of D.S. Stewart and a Postdoctoral student H.I. Lee at the University of Illinois.
Author:
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ISBN:
Category :
Languages : en
Pages :
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Book Description
We summarize recent investigations into the theory of multi-dimensional, time-dependent detonation. These advances have led to the development of a theory for describing the propagation of high-order detonation in condensed-phase explosives. The central approximation in the theory is that the detonation shock is weakly curved. Specifically, we assume that the radius of curvature of the detonation shock is large compared to a relevant reaction-zone thickness. Our main findings are: (1) the flow is quasi-steady and nearly one dimensional along the normal to the detonation shock; and (2) the small deviation of the normal detonation velocity from the Chapman-Jouguet (CJ) value is generally a function of curvature. The exact functional form of the correction depends on the equation of state (EOS) and the form of the energy-release law. 8 refs.
Author: F. Zhang
Publisher: Springer Science & Business Media
ISBN: 3642229670
Category : Science
Languages : en
Pages : 482
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Book Description
This book, as a volume of the Shock Wave Science and Technology Reference Library, is primarily concerned with the fundamental theory of detonation physics in gaseous and condensed phase reactive media. The detonation process involves complex chemical reaction and fluid dynamics, accompanied by intricate effects of heat, light, electricity and magnetism - a contemporary research field that has found wide applications in propulsion and power, hazard prevention as well as military engineering. The seven extensive chapters contained in this volume are: - Chemical Equilibrium Detonation (S Bastea and LE Fried) - Steady One-Dimensional Detonations (A Higgins) - Detonation Instability (HD Ng and F Zhang) - Dynamic Parameters of Detonation (AA Vasiliev) - Multi-Scaled Cellular Detonation (D Desbordes and HN Presles) - Condensed Matter Detonation: Theory and Practice (C Tarver) - Theory of Detonation Shock Dynamics (JB Bdzil and DS Stewart) The chapters are thematically interrelated in a systematic descriptive approach, though, each chapter is self-contained and can be read independently from the others. It offers a timely reference of theoretical detonation physics for graduate students as well as professional scientists and engineers.
Author:
Publisher: AIAA
ISBN: 9781600863875
Category : Detonation waves
Languages : en
Pages : 422
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 29
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Book Description
Experiments on the HMX-based, condensed explosive PBX-9501 were carried out to validate a reduced asymptotically derived description of detonation shock dynamics (DSD). The experiments, coined passover experiments' have embedded disks of lead in right circular cylinders of PBX-9501. A range of dynamically changing states, with both divergent and convergent shock shapes are realized as a detonation front is created on one end of the cylinder and passes over the embedded disk of lead. The time-of-arrival of the detonation shock at the output end of the cylinder is recorded and compared against simulations using the DSD model. The experiment and DSD theory are found to be in excellent agreement and offer a high-fidelity, yet computationally efficient means for complex wave-front tracking in explosive systems.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
The research carried out by this contract was part of a larger effort funded by LANL in the areas of deflagration to detonation in porous energetic materials (DDT) and detonation shock dynamics in high explosives (DSD). In the first three years of the contract the major focus was on DDT. However, some researchers were carried out on DSD theory and numerical implementation. In the last two years the principal focus of the contract was on DSD theory and numerical implementation. However, during the second period some work was also carried out on DDT. The paper discusses DDT modeling and DSD modeling. Abstracts are included on the following topics: modeling deflagration to detonation; DSD theory; DSD wave front tracking; and DSD program burn implementation.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
High energy explosives are used in a variety of applications, from military to industrial processes. The use of embedded, inert material "wave shapers" is a primary method to customize the detonation front for desired ex-plosive applications. These systems create detonation states that do not follow the simple line of sight, or Huy-gens model and, hence, advanced detonation physics with associated theory are required. The theory of detonation shock dynamics (DSD) is one such description used to provide high fidelity modeling of complex wave structures. A collection of experiments using ultra-high speed cameras is presented as a means of obtaining spatial and temporal characteristics of complex detonation fronts that validate the DSD descriptions. The method of test, operational conditions and results are given to demonstrate the use of high-rate imaging of detonation events and how this validates our understanding of the physics and the capability of advanced detonation wave tracking models.
Author: Peter O. K. Krehl
Publisher: Springer Science & Business Media
ISBN: 3540304215
Category : Science
Languages : en
Pages : 1298
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Book Description
This unique and encyclopedic reference work describes the evolution of the physics of modern shock wave and detonation from the earlier and classical percussion. The history of this complex process is first reviewed in a general survey. Subsequently, the subject is treated in more detail and the book is richly illustrated in the form of a picture gallery. This book is ideal for everyone professionally interested in shock wave phenomena.
Author: Juan A. Saenz
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
We investigate the ignition and dynamics of detonation waves in condensed phase explosives using direct numerical simulations and asymptotic analysis. We develop a model to simulate deflagration to detonation transition in pentaerythritol tetranitrate 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. We suggest phenomenological closure relations, consistent with the limit of a compressible inert material and of a solid fully reactive material, such that the equation of state can be posed only in terms of mixture quantities and the reaction and compaction variables. We demonstrate the model's ability to capture deflagration to detonation transition in pentaerythritol tetranitrate powders by matching transients typically observed in experiments, through simulation. We develop an asymptotic formulation to calculate an intrinsic relation between the shock acceleration, velocity and curvature of self-sustained detonation waves in the limit of small time variation and small curvature of the lead shock front in condensed phase explosives. The formulation is developed in terms of a general, incomplete equation of state with composition variables to represent scalar quantities for a general range of phenomena. The results presented here are the first calculations obtained from asymptotic detonation shock dynamics relations for general material models. The formulation is a generalization of an asymptotic theory for a polytropic equation of state and a single step Arrhenius reaction rate model. We discuss the assumptions and justify the generalizations made that allow the use of general form incomplete equations of state. We test the proposed theory by calculating quasi-steady relations between detonation velocity and curvature and the dynamics of ignition events in a reactive hydrogen-oxygen mixture using an ideal equation of state and single step Arrhenius reaction rate model, and compare the results with those obtained using the original asymptotic theory. We find that quasi-steady relations between detonation velocity and curvature calculated using the proposed theory are in better agreement with numerical calculations than the original theory. We also use an equation of state that realistically represents condensed phase explosives, and two composition variables to track reaction and compaction processes, to perform calculations of quasi-steady relations between detonation velocity and curvature, detonation shock acceleration fields as a function of detonation velocity and curvature, and the dynamics of ignition events in solid PBX9501 and in PETN powders. We compare our results with numerical calculations of detonation shock dynamics and direct numerical simulations. We find that the time it takes an ignition wave to become quasi-steady is short, explaining why the quasi-steady relation between the detonation velocity and curvature can sometimes be a good approximation for a speed rule.
