A Validation of First-Order Detonation Shock Dynamics Theory PDF Download
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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:
Publisher:
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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.
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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.
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Languages : en
Pages : 29
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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: D. Scott Stewart
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 56
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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: D. Scott Stewart
Publisher:
ISBN:
Category : Detonation waves
Languages : en
Pages : 50
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Author: Juan A. Saenz
Publisher:
ISBN:
Category :
Languages : en
Pages :
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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.
Author: D. Scott Stewart
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 0
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Author:
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ISBN:
Category :
Languages : en
Pages : 24
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Author: Wildon Fickett
Publisher: Univ of California Press
ISBN: 9780520051256
Category : Science
Languages : en
Pages : 272
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