Download or read book Numerical Simulation of Detonation in Condensed Phase Explosives written by D. A. Jones and published by . This book was released on 1998 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detonation Shock and Ignition Dynamics in Condensed Phase Explosives written by Juan A. Saenz and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Numerical Modelling of Detonation and Ignition of Condensed Phase Explosives written by Simon David Wilkinson and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detonation of Condensed Explosives written by Roger Cheret and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work marks a stage in the evolution of a scientific and technical field which has been developed by the Commissariat a l'Energie Atomique (CEA) over several decades. Many members of the staff of the CEA have won re nown in this field, and their work has brought it to the high degree of excel lence for which it is internationally recognized today. These scientists had to consider every aspect of the field, as it concerned: modeling, which has recourse to fluid thermodynamics, molecular phys ics, and chemistry; numerical evaluation, which relies on mathematical analysis and data processing; and experiments in the firing area, which require specific stress generators and instrumentation. Whilst this book is a testament to the activity and success of staff of the CEA, it also reviews a number ofthe advances made in the discipline. How ever, it is not intended to be an exhaustive account of those advances; it is assumed that the reader can, if desired, consult the standard monographs, and more recent, more specialized works (notably W.C. Davis and W. Fickett, and C.L. Mader). The history of the discipline is interesting in itself, and also as an illustra tion of the causes which lead to progress in a coherent body of scientific work. I should like to make some comments on this progress, of which there is a fascinating summary in the introduction, and which will figure largely throughout the work.
Download or read book Detonation Phenomena of Condensed Explosives written by Shiro Kubota and published by Springer Nature. This book was released on 2023-01-13 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents fundamental theory of shock and detonation waves as well as selected studies in detonation research in Japan, contributed by selected experts in safety research on explosives, development of industrial explosives, and application of explosives. It also reports detonation research in Japan featuring industrial explosives that include ammonium nitrate-based explosives and liquid explosives. Intended as a monographic-style book, it consistently uses technical terms and symbols and creates organic links between various detonation phenomena in application of explosives, fundamental theory of detonation waves, measurement methods, and individual studies. Among other features, the book presents a historical perspective of shock wave and detonation research in Japan, pedagogical materials for young researchers in detonation physics, and an introduction to works in Japan, including equations of state, which are worthy of attention but about which very little is known internationally. Further, the concise pedagogical chapters also characterize this book as a primer of detonation of condensed explosives and help readers start their own research.
Download or read book Numerical Modeling of Explosives and Propellants written by Charles L. Mader and published by CRC Press. This book was released on 2007-10-18 with total page 539 pages. Available in PDF, EPUB and Kindle. Book excerpt: Major advances, both in modeling methods and in the computing power required to make those methods viable, have led to major breakthroughs in our ability to model the performance and vulnerability of explosives and propellants. In addition, the development of proton radiography during the last decade has provided researchers with a major new experimental tool for studying explosive and shock wave physics. Problems that were once considered intractable – such as the generation of water cavities, jets, and stems by explosives and projectiles – have now been solved. Numerical Modeling of Explosives and Propellants, Third Edition provides a complete overview of this rapidly emerging field, covering basic reactive fluid dynamics as well as the latest and most complex methods and findings. It also describes and evaluates Russian contributions to the experimental explosive physics database, which only recently have become available. This book comes with downloadable resources that contain— · FORTRAN and executable computer codes that operate under Microsoft® Windows Vista operating system and the OS X operating system for Apple computers · Windows Vista and MAC compatible movies and PowerPoint presentations for each chapter · Explosive and shock wave databases generated at the Los Alamos National Laboratory and the Russian Federal Nuclear Centers Charles Mader’s three-pronged approach – through text, computer programs, and animations – imparts a thorough understanding of new computational methods and experimental measuring techniques, while also providing the tools to put these methods to effective use.
Download or read book Detonation in Condensed Explosives written by James Taylor and published by . This book was released on 1952 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Formation Propagation and Stability of Self Sustained Detonation Waves in Gaseous Mixtures Condensed Phase Explosives and Media With Hydraulic Resistance written by Victor Gorshkov and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition from Deflagration to Detonation in Condensed Phases written by Aleksandr Fedorovich Beli︠a︡ev and published by . This book was released on 1975 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous ed.: Izdatel'stvo Nauka, Moskva, 1973.
Download or read book Instability of Steady and Quasi steady Detonations written by Brian D. Taylor and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The stability properties and dynamic behavior of steady and quasi-steady detonation theories are investigated through linear stability analysis and numerical simulation. A general, unsteady, three-dimensional formulation of the reactive Euler equations in a shock-fitted reference frame is derived. The formulation is specialized to three configurations: planar one-dimensional detonation, radially symmetric one-dimensional detonation, and two-dimensional detonation in a rectangular channel. High-order convergent numerical simulation schemes for these configurations are derived and used to study the linear and nonlinear stability of detonations. Shock-fitted numerical simulation is used to study the two-dimensional instability of steady solutions to the Zel'dovich, von Neumann, and Doring (ZND) model of detonation. It is demonstrated through several methods of analysis that the dependence of instability growth rates and oscillation frequencies on the initial disturbance wavelength, as predicted by linear stability theory, is quantitatively reproduced by shock-fitted simulations. Agreement with the theorized temporal and spatial structure of the instability is demonstrated by a functional expansion of the solution perturbations, obtained from simulation data, in terms of the linear stability eigenfunctions. Three regimes of unstable behavior - linear, weakly non-linear, and fully non-linear - are explored and characterized in terms of the power spectrum of the normal detonation velocity. Using solutions obtained from Detonation Shock Dynamics (DSD) theory, the behavior of cylindrically and spherically expanding symmetric detonations is studied by one-dimensional shock-fitted numerical simulation. We consider idealized models of gaseous and condensed phase detonation, as well as a realistic model calibrated for the high explosive PBX-9501. We study the behavior of detonations initialized with solutions of DSD as they expand radially. The various models and calibrations exhibit regimes of hydrodynamic stability, in which the detonation evolves slowly in time and agreement with DSD theory is good, and regimes of instability, which in some cases leads to failure of the detonation wave.
Download or read book The Hydrodynamic Hot Spot and Shock Initiation of Homogeneous Explosives written by Charles L. Mader and published by . This book was released on 1962 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detonation Properties of Condensed Explosives Computed Using the Becker Kistiakowsky Wilson Equation of State written by Charles L. Mader and published by . This book was released on 1963 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Detonation Transfer Between Gaseous Explosive Layers written by David Allen Jones and published by . This book was released on 1989 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Gas phase Detonation Transmission written by Elaine S. Oran and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanoscale Simulations of Detonation written by Andrew Joseph Heim and published by . This book was released on 2007 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fundamental study of detonation physics phenomena is presented utilizing Molecular Dynamics (MD) with the popular Reactive Emperical Bond Order (REBO) potential. We explore the effects that varying the strength of the interatomic bonding potentials of the reactive chemical species have on the detonation properties, shock velocity and critical width for sustained detonation. We conduct a much more thorough analysis of the thermodynamic properties of that model than has been done previously in order to quantitatively compare our observations with established theories. During this analysis, we discover some unconventional properties of the model. Using physical reasoning, we track down the cause of these unconventional thermodynamic behaviors and resolve them so that the model behaves more consistently with conventional systems, that is, more molecular ones as organic high explosives tend to be. In clearing up these issues with the model, we introduce into it the phenomenon of detonation instability, whereby transverse waves in the locally subsonic reaction zone influence the detonation propagation. This has never before been seen in MD simulations of detonation but is known well by experimentalists and continuum modelers.
Download or read book Numerical Simulations of the Cellular Structure of Detonations in Liquid Nitromethane Regularity of the Cell Structure written by R. Guirguis and published by . This book was released on 1986 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detailed structure of planar detonation waves in liquid nitromethane was studied using time-dependent two-dimensional numerical simulations. The walls are assumed to heavily confine the liquid explosive and boundary layer effects are neglected. The solution thus simulates the detonation structure near the center of a wide channel. Chemical decomposition of nitromethane is described by a two-step model composed of an induction time followed by energy release. A simplified equation of state based on the Walsh and Christian technique for condensed phases and the BKW equation of state for gas phases is used. When mixtures of both phases are present, pressure and temperature equilibrium between them is assumed. The simulations show a cellular pattern traced by a system of triple points dividing the detonation front into sections. However, a substructure of weaker triple points also trace out a non-uniform pattern within the main pattern, resulting in an irregular cellular structure. A correlation exists between the regularity of the cellular pattern and both the curvature of the front and the change in induction zone thickness at the triple points. If the induction time is a stronger function of temperature, the weaker triple points disappear and a a more regular structure is produced. We conclude that the regularity of the cellular pattern is strongly influenced by the temperature-dependence of the induction time.
Download or read book Numerical Simulation of Detonation Initiation by the Space time Conservation Element and Solution Element Method written by Bao Wang and published by . This book was released on 2010 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This dissertation is focused on the numerical simulation of the detonation initiation process. The space-time Conservation Element and Solution Element (CESE) method, a novel numerical method for time-accurate solutions of nonlinear hyperbolic equations, is extended to model conservation laws with stiff source terms for the detonation initiation process with multiple-step, finite-rate chemistry. The first part of the dissertation illustrates the numerical framework for unsteady chemically reacting flows by incorporating multiple-step, finite-rate chemical mechanisms using the CESE method. One- and two-dimensional solvers have been developed. Extensive code validation and verification are provided for the one- and two-dimensional CESE solvers. The second part focuses on the numerical investigation of the detonation initiation process. The numerical framework is first applied to the direct initiation of gaseous detonations by a blast wave. One-dimensional cylindrical and spherical direct initiation processes in a hydrogen-oxygen mixture are studied with a twenty-four step chemical reaction model. Structures of unsteady reaction zone are clearly resolved. The competition between heat release rate, front curvature, and unsteadiness is investigated. Detailed wave movements in the detonation wave front show that nonlinear waves play an important role in the reacceleration process and are the key to understanding the detonation failure mechanism. The detonation initiation process by implosion shock is then investigated. Shock focusing and shock interactions in the detonation initiation process are examined. Results show a two-shock implosion system due to the interaction between the reflected primary shock and the imploding contact discontinuity. Oblique detonation is studied for the code verification and validation of the two-dimensional CESE solvers. Stabilized detonation structures are resolved and the length of the induction zone is compared with point ignition test data. Implosion with polygonal shock fronts is then explored. Similar to the findings in the one-dimensional results, pressure histories in the focal region show multiple implosions. This Ph. D. study work applies the very accurate and efficient CESE method to study detonation initiation processes. The resultant solvers are state-of-the-art numerical codes that are ready to be applied to time-accurate solutions of detonation initiation processes. This approach provides a new numerical framework for high-fidelity simulations of detonation initiation.
