Download or read book A Thermal Mechanical Model of Deflagration to Detonation in Granular Energetic Materials written by M. R. Baer and published by . This book was released on 1984 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we present a multiphase, reactive flow model, based on the theory of mixtures and utilize it to describe deflagration-to-detonation transition in granular explosives and propellants. This nonequilibrium model treats each phase as fully compressible and incorporates a dynamic compaction model for the granular reactant. Formulation of the constitutive models include a pressure-dependent burn rate and experimentally-determined porous bed permeability. Numerical solutions of the one-dimensional Eulerian equations are obtained using an implicit method-of-lines solver. The model has examined two exlosives: CP and HMX. Predictions with this model agree with existing experimental observations and demostrate that a thermodynamically-consistent multiphase model can describe the flame-spread processes of convective burning and detonation.

Download or read book Engineering Models of Deflagration to detonation Transition written by and published by . This book was released on 1995 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the past two years, Los Alamos has supported research into the deflagration-to-detonation transition (DDT) in damaged energetic materials as part of the explosives safety program. This program supported both a theory/modeling group and an experimentation group. The goal of the theory/modeling group was to examine the various modeling structures (one-phase models, two-phase models, etc.) and select from these a structure suitable to model accidental initiation of detonation in damaged explosives. The experimental data on low-velocity piston supported DDT in granular explosive was to serve as a test bed to help in the selection process. Three theoretical models have been examined in the course of this study: (1) the Baer-Nunziato (BN) model, (2) the Stewart-Prasad-Asay (SPA) model and (3) the Bdzil-Kapila-Stewart model. Here we describe these models, discuss their properties, and compare their features.

Download or read book Modeling Thermally Driven Energetic Response of High Explosives written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have improved our ability to model the response of energetic materials to thermal stimuli and the processes involved in the energetic response. Traditionally, the analyses of energetic materials have involved coupled thermal transport/chemical reaction codes. This provides only a reasonable estimate of the time and location of ensuing rapid reaction. To predict the violence of the reaction, the mechanical motion must be included in the wide range of time scales associated with the thermal hazard. The ALE3D code has been modified to assess the hazards associated with heating energetic materials in weapons by coupling to thermal transport model and chemistry models. We have developed an implicit time step option to efficiently and accurately compute the hours of heating to reaction of the energetic material. Since, on these longer time scales materials can be expected to have significant motion, it is even more important to provide high-order advection for all components, including the chemical species. We show two examples of coupled thermal/mechanical/chemical models of energetic materials in thermal environments.

Download or read book Modeling and Numerical Simulation of Deflagration to detonation Transition in Porous Energetic Materials written by Shaojie Xu and published by . This book was released on 1996 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: An understanding of the deflagration-to-detonation transition (DDT) in porous energetic materials is important for various engineering applications. Safety issues for damaged explosives is one example. In this work, two topics related to multi-dimensional simulation of DDT in energetic materials are presented. The objective of the first part is to develop a simple and predictive model for multidimensional simulations. Models constructed by two-phase mixture theory usually have complicated mathematical formulation, and admit complex dispersive wave structures. Three simplified single-velocity models, named BKS, SVG and GISPA, are considered in this work. The BKS model was derived--using asymptotic theory--from the two-phase theory by assuming a large interphase drag. The SVG model is newly developed, based on solid-void-gas three-phase formulation. The GISPA model is a new single-phase model which utilizes two independent rate processes for compaction and reaction. In addition to model simplification, a new reaction rate law is developed which describes the slow and the fast energy-release processes during DDT. A comparative study is carried out and the study shows that the SVG and GISPA models are able to predict all the events measured in 1-D DDT-tube experiments. The second part of the study describes the development of a high-quality numerical method for two-dimensional DDT simulations. The new fourth-order method integrates total variation diminishing and essentially non-oscillatory schemes with an extension to a general equation of state. In order to handle complex geometry, an internal boundary algorithm is developed on a structured grid, which allows a two-dimensional, non-deformable body of an arbitrary shape to be inserted in a flow field. A DDT simulation is carried out for cases of both blunt-body and sharp-body impact on porous energetic materials. The radius effect (in the case of blunt-body impact) and the angle effect (in the case of sharp-body impact) on detonation properties are studied.

Download or read book Energetic Materials Synthesis to Detonation written by Taylor Sandoval Busby and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation on Deflagration to Detonation Transition in Porous Energetic Materials Final Report written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theory and Modeling of Thermal Reaction Propagation in Beam Initiated Explosives written by J. B Aviles (Jr) and published by . This book was released on 1993 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous work on the thermal initiation of energetic materials by particle beams concentrated on uniformly irradiated confined samples. The present report extends the work to situations where only a portion of the material has been irradiated. In some materials (e.g., TATB) only the irradiated region undergoes thermal initiation; in other materials a thermal initiation front has been observed (by thermocouple response) to propagate away from the irradiated region. The frontal speeds are of the order of centimeters per second to tens of centimeters per second. These slow speeds eliminate the possibility of pressure propagation or a deflagration to detonation transition (DDT). Modeling is based on the interference that at the thermal initiation temperature the material develops a greatly enhance thermal and gaseous diffusivity. This allows the exothermic energy released to propagate into the cold region and forestalls any explosive temperature rise. At a well defined positive R* (the explosion radius) thermal initiation propagation ceases and an explosive temperature rise takes place.

Download or read book Decomposition Combustion and Detonation Chemistry of Energetic Materials written by Thomas B. Brill and published by . This book was released on 1996 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energetic materials are distinguished from other materials primarily by the fact that rapid, exothermic reactions can be induced with the release of gaseous products. This complex phenomenon cuts across many boundaries of chemistry (synthesis, kinetics, thermodynamics, spectroscopy, quantum and molecular dynamics calculations, etc.) and engineering physics (shock and detonation waves, hydrodynamics, fracture and solid mechanics, defects, etc.). This volume offers the latest chemistry advancements in understanding the complex dynamic processes in these materials in the condensed phase. The focus is on fundamental research into the rates and pathways of rapid exothermic reactions, product specification, diagnostic methods, molecular processes of energy transfer, and molecular processes at extreme pressure and temperature. Many novel materials are discussed.

Download or read book Hydrocode Modeling of Deflagration and Detonation with Dynamic Compaction of a Granular Explosive written by Kelly Susan Mahon and published by . This book was released on 2015 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deflagration to Detonation Transition in Granular HMX written by Nathan Burnside and published by . This book was released on 2001 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling of Deflagration to Shock to Detonation Transition DSDT in Porous High Energy Solid Propellants and Explosives written by Herman W. Krier and published by . This book was released on 1982 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: This annual report represents the summary of work done on the modeling of processes leading from deflagration to detonation in porous or granular high energy propellants. Particular attention is paid to the analysis of shock development from compression waves forming ahead of confined burning in the original material. It is summarized that if the shock is sufficiently strong, it will lead to shock to detonation transition (SDT). During the development of the shock wave, the porous material may collapse into a solid plug of void free propellant because the speed at which the wave propagates increases as the material is compressed. The modeling effort presented indicates how two-phase unsteady combustion processes in granular material can couple to the solid mechanics of shock formation and eventually to a steady-state detonation. (Author).

Download or read book Missale Cistercience juxta novissimam Romani recogniti correctionem editum written by and published by . This book was released on 1788 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ensekigaisen ni yoru kakuy g purazuma no shindan keisoku kenky h kokusho written by and published by . This book was released on 1980 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energetic Materials Detonation combustion written by Peter Politzer and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulating the Thermal Response of High Explosives on Time Scales of Days to Microseconds written by M. A. McClelland and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present an overview of computational techniques for simulating the thermal cookoff of high explosives using a multi-physics hydrodynamics code, ALE3D. Recent improvements to the code have aided our computational capability in modeling the response of energetic materials systems exposed to extreme thermal environments, such as fires. We consider an idealized model process for a confined explosive involving the transition from slow heating to rapid deflagration in which the time scale changes from days to hundreds of microseconds. The heating stage involves thermal expansion and decomposition according to an Arrhenius kinetics model while a pressure-dependent burn model is employed during the explosive phase. We describe and demonstrate the numerical strategies employed to make the transition from slow to fast dynamics.

Download or read book Analysis of a Two temperature Model of Deflagrations in Confined Porous Energetic Materials written by Stephen B. Margolis and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Complete Blow Up for Parabolic System Arising in a Theory of Thermal Explosion of Porous Energetic Materials written by Thomas Ian Hill and published by . This book was released on 2015 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we consider a natural generalization of classical Frank-Kamenetskii theory of thermal explosion (autoignition) to single phase porous energetic materials. The resulting model consists of a system of two reaction diffusion equations with a super-linear reaction term posed in a smooth bounded domain with Dirichlet boundary conditions. This model describes the initial state of evolution of temperature and pressure fields in reactive porous media. In a framework of this model, successful autoignition is associated with a blow up of the solution for the system under consideration (here, "blow up" means that the solution becomes unbounded in finite time). We show that if blow up takes place then it is complete; that is, a solution can not be prolonged in any reasonable weak sense for any time after blow up. From a physical perspective this means that if autoignition takes place, then it occurs in the entire domain occupied by the porous material. This result is a generalization of a similar result for classical Frank-Kamenetskii model obtained in [1].