Download or read book Engineering Models of Deflagration to detonation Transition written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Numerical Modeling of the Deflagration to detonation Transition written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of a confined porous bed of burning explosive in contact with a solid explosive is studied by computer simulation. The burning is modeled using a bulk burn model that is a function of the surface area and the pressure. Once pressure excursions occur from the confined burning the transition to detonation is modeled using a pressure-dependent heterogeneous explosive shock decomposition model called Forest Fire. The occurrence of detonation in the solid explosive is shown to be dependent upon the surface-to-volume ratio, the confinement of the porous bed, and the geometry of the system.

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 Major Research Topics in Combustion written by M.Y. Hussaini and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 668 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Institute for Computer Applications in Science and Engineer ing (ICASE) and NASA Langley Research Center (LaRC) brought together on October 2-4, 1989 experts in the various areas of com bustion with a view to expose them to some combustion problems of technological interest to LaRC and possibly foster interaction with the academic community in these research areas. The top ics chosen for this purpose were flame structure, flame stability, flame holding/extinction, chemical kinetics, turbulence-kinetics in teraction, transition to detonation, and reacting free shear layers. The lead paper set the stage by discussing the status and issues of supersonic combustion relevant to scramjet engine. Then the ex perts were called upon i) to review the current status of knowledge in the aforementioned ;:I. reas, ii) to focus on how this knowledge can be extended and applied to high-speed combustion, and iii) to suggest future directions of research in these areas. Each topic was then dealt with in a position paper followed by formal discussion papers and a general discussion involving the participants. The position papers discussed the state-of-the-art with an emphasis on key issues that needed to be resolved in the near future. The discussion papers crit ically examined these issues and filled in any lacunae therein. The edited versions of the general discussions in the form of questions from the audience and answers from the speakers are included wher ever possible to give the reader the flavor of the lively interactions that took place.

Download or read book The Detonation Phenomenon written by John H. S. Lee and published by Cambridge University Press. This book was released on 2008-06-30 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the detonation phenomenon in explosives. It is ideal for engineers and graduate students with a background in thermodynamics and fluid mechanics. The material is mostly qualitative, aiming to illustrate the physical aspects of the phenomenon. Classical idealized theories of detonation waves are presented first. These permit detonation speed, gas properties ahead and behind the detonation wave, and the distribution of fluid properties within the detonation wave itself to be determined. Subsequent chapters describe in detail the real unstable structure of a detonation wave. One-, two-, and three-dimensional computer simulations are presented along with experimental results using various experimental techniques. The important effects of confinement and boundary conditions and their influence on the propagation of a detonation are also discussed. The final chapters cover the various ways detonation waves can be formed and provide a review of the outstanding problems and future directions in detonation research.

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 Performance Impact of Deflagration to Detonation Transition Enhancing Obstacles written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-18 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A sub-model is developed to account for the drag and heat transfer enhancement resulting from deflagration-to-detonation (DDT) inducing obstacles commonly used in pulse detonation engines (PDE). The sub-model is incorporated as a source term in a time-accurate, quasi-onedimensional, CFD-based PDE simulation. The simulation and sub-model are then validated through comparison with a particular experiment in which limited DDT obstacle parameters were varied. The simulation is then used to examine the relative contributions from drag and heat transfer to the reduced thrust which is observed. It is found that heat transfer is far more significant than aerodynamic drag in this particular experiment. Paxson, Daniel E. and Schauer, Frederick and Hopper, David Glenn Research Center NASA/TM-2012-217629, AIAA Paper 2009-502, E-18219

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 Performance Impact of Deflagration to Detonation Transition Enhancing Obstacles written by Daniel E. Paxson and published by BiblioGov. This book was released on 2013-07 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: A sub-model is developed to account for the drag and heat transfer enhancement resulting from deflagration-to-detonation (DDT) inducing obstacles commonly used in pulse detonation engines (PDE). The sub-model is incorporated as a source term in a time-accurate, quasi-onedimensional, CFD-based PDE simulation. The simulation and sub-model are then validated through comparison with a particular experiment in which limited DDT obstacle parameters were varied. The simulation is then used to examine the relative contributions from drag and heat transfer to the reduced thrust which is observed. It is found that heat transfer is far more significant than aerodynamic drag in this particular experiment.

Download or read book Universal Model Method of Determination of Deflagration to Detonation Transition Susceptibility of Various Class Explosive Materials written by Soviet Union and published by . This book was released on 1989 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation of the Transition from Deflagration to Detonation written by G. Goyal and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 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 Krier and published by . This book was released on 1982 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Deflagration to Detonation Transition Ddt in Hydrogen Explosions written by P. Middha 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 Combustion Processes in Propulsion written by Gabriel Roy and published by Butterworth-Heinemann. This book was released on 2006 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical propulsion comprises the science and technology of using chemical reactions of any kind to create thrust and thereby propel a vehicle or object to a desired acceleration and speed. Cumbustion Processes in Propulsion focuses on recent advances in the design of very highly efficient, low-pollution-emitting propulsion systems, as well as advances in testing, diagnostics and analysis. It offers unique coverage of Pulse Detonation Engines, which add tremendous power to jet thrust by combining high pressure with ignition of the air/fuel mixture. Readers will learn about the advances in the reduction of jet noise and toxic fuel emissions-something that is being heavily regulated by relevant government agencies. Lead editor is one of the world's foremost combustion researchers, with contributions from some of the world's leading researchers in combustion engineering Covers all major areas of chemical propulsion-from combustion measurement, analysis and simulation, to advanced control of combustion processes, to noise and emission control Includes important information on advanced technologies for reducing jet engine noise and hazardous fuel combustion emissions

Download or read book Deflagration to Detonation Transition Processes in Pulsed Detonation Engines written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of the work performed in the current contract is to assess the accuracy of potential modelling techniques applied to the formation of Deflagration to Detonation (DDT) kernels in mixtures of hydrocarbons with air. The application area is of direct relevance to the transition to detonation in pulsed detonation engines featuring premixed gases. The latter technology is currently pursued at Wright Laboratories and the current evaluation is directly linked to this technology. Key aspects covered include guidance on suitable theoretical development directions and a preliminary investigation of optimal conditions for transition to detonation. The work is technically demanding and features several aspects that has not previously been accomplished. The main conclusions of the study are perhaps surprisingly positive. The work does show, for the first time, that the application of higher moment closures to model the initial onset of DDT is technically possible. Furthermore, the work illustrates that two physical limits on the chemical source term closure does in most cases bracket the experimental data. It is also shown that the transported PDF approach can be successfully applied to the modelling of premixed turbulent flames with scalar spaces of sufficient size to model auto-ignition type phenomena. It is also evident from the current work that the modelling of explosion kernels in pre-existing turbulence fields is very sensitive to both the details of the injection process and to the chemical source term closure. The present work does lay the foundations and also indicates the directions for further studies.