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Numerical Modelling Of Detonation Initiation Via Shock Interaction With Multiple Flames
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Book Synopsis Numerical Modelling of Detonation Initiation Via Shock Interaction with Multiple Flames by : Georgios Bakalis
Download or read book Numerical Modelling of Detonation Initiation Via Shock Interaction with Multiple Flames written by Georgios Bakalis and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Detonation in gaseous mixtures is a phenomenon of great importance for explosion safety assessment in hydrogen economy and for the development of advanced detonation-based propulsion systems. In practical applications, a detonation is generally caused by a deflagration to detonation transition (DDT) since a smaller amount of energy is required compared to a direct initiation. The key issue of DDT is finding the appropriate mechanisms to rapidly generate the detonation waves with a relatively weak ignition source. The objective of this work is to study numerically the possibility of DDT resulting from shock-multiple cylindrical flames interaction. The numerical setup aims to mimic an array of laminar flames ignited at different spark times, artificially inducing chemical activity to stimulate the coupling between the gasdynamics and the chemical energy release for the transition of deflagration-to-detonation. Using numerical simulations, a number of physical parameters are varied to determine their effect on the run-up distance as well as the time until the onset of detonation occurs, and to explore any scaling relationship among different them. The two-dimensional Navier-Stokes equations with one-step Arrhenius chemistry including the effects of viscosity, thermal conduction and molecular diffusion are used for the simulations. For comparison, simulations with Euler equations are also performed. The finite-volume operator splitting scheme used is based on the 2nd order Godunov-type, Weighted Average Flux (WAF) method with an approximate HLLC Riemann Solver. An Adaptive Mesh Refinement (AMR) technique is used to increase the resolution in areas of interest. The simulation results show that the interaction of the weak shock with the first cylindrical flame demonstrates very good agreement with the results in the literature and that a single weak shock-flame interaction was not enough to cause prompt DDT. However, a high degree of Richtmyer-Meshkov instabilities induced by repeated shock-flame interactions along with shock-boundary interactions generate turbulence that accelerates the flame brush, until eventually a hot spot ignition in the unreacted material develops into a multi-headed detonation wave. The simulation results also show that DDT is sensitive to the simulation method and that certain simulation parameters significantly affect the DDT phenomenon.
Book Synopsis Detonation-wave Interactions. [PBX-9404]. by :
Download or read book Detonation-wave Interactions. [PBX-9404]. written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The interaction of laterally colliding, diverging, cylindrical detonation waves in PBX-9404 has been studied using the radiographic machine PHERMEX and the two-dimensional, reactive Lagrangian hydrodynamic code 2DL. The experimentally observed flow could be numerically reproduced using the Forest Fire heterogeneous shock initiation burn model which permits realistic numerical simulation of the burning region of regular and diverging detonation waves, and the interacting detonation waves undergoing regular and Mach reflection. The interaction of two, three, and five colliding, diverging spherical detonation waves in PBX-9404 has been numerically modeled using the three-dimensional, reactive Eulerian hydrodynamic code 3DE. The size and magnitude of the high pressure double, triple, quadruple, and quintuple interactions depends significantly upon the number and relative locations of initiators. The initiation of propagating detonation in the insensitive explosive PBX-9502 by triple shock-wave interaction resulting from three initiators has been studied using the 3DE code with Forest Fire kinetics.
Book Synopsis Numerical Simulation of Detonation Initiation by the Space-time Conservation Element and Solution Element Method by : Bao Wang
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.
Book Synopsis Numerical Calculation of Shock-induced Initiation of Detonations. [PBX 9501]. by :
Download or read book Numerical Calculation of Shock-induced Initiation of Detonations. [PBX 9501]. written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of some numerical calculations of the impact of steel cylinders and spheres on the plastic-bonded high explosive PBX 9501 are described. The calculations were carried out by a reactive, multicomponent, two-dimensional, Eulerian hydrodynamic computer code, 2DE. The 2DE computer code is a finite difference code that uses the donor-acceptor-cell method to compute mixed cell fluxes. The mechanism of shock initiation to detonation in heterogeneous explosives is best described as local decomposition at hot spots that are formed by shock interactions with density discontinuities. The liberated energy strengthens the shock so that as it interacts with additional inhomogeneities, hotter hot spots are formed, and more of the explosive is decomposed. The shock wave grows stronger until a detonation begins. This mechanism of initiation has been described numerically by the Forest Fire burn model, which gives the rate of explosive decomposition as a function of local pressure. The parameters in the Forest Fire burn model have been developed from experiments where the induced shock approximates a plane wave and are applied, in this case, to a situation where the induced shock is a divergent wave with curvature that depends on the size and shape of the projectile. The calculated results have been compared with results from experiments involving instrumented mock and live high explosives, with projectiles of varying sizes, shapes, and velocities. We find that there is good agreement between the calculated and experimental data.
Book Synopsis Numerical Modeling of Explosives and Propellants, Second Edition by : Charles L. Mader
Download or read book Numerical Modeling of Explosives and Propellants, Second Edition written by Charles L. Mader and published by CRC Press. This book was released on 1997-08-29 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Charles Mader, a leading scientist who conducted theoretical research at Los Alamos National Laboratory for more than 30 years, sets a new standard with this reference on numerical modeling of explosives and propellants. This book updates and expands the information presented in the author's landmark work, Numerical Modeling of Detonations, published in 1979 and still in use today. Numerical Modeling of Explosives and Propellants incorporates the considerable changes the personal computer has brought to numerical modeling since the first book was published, and includes new three-dimensional modeling techniques and new information on propellant performance and vulnerability. Both an introduction to the physics and chemistry of explosives and propellants and a guide to numerical modeling of detonation and reactive fluid dynamics, Numerical Modeling of Explosives and Propellants offers scientists and engineers a complete picture of the current state of explosive and propellant technology and numerical modeling. The book is richly illustrated with figures that support the concepts, and filled with tables for quick access to precise data. The accompanying CD-ROM contains computer codes that are the national standard by which modeling is evaluated. Dynamic material properties data files and animation files are also included. There is no other book available today that offers this vital information.
Book Synopsis The Modelling of Shock Initiation of Detonation in High Explosives Using the EPIC 2 Hydrocode with the Forest Fire Model by : Ijsselstein R. R.
Download or read book The Modelling of Shock Initiation of Detonation in High Explosives Using the EPIC 2 Hydrocode with the Forest Fire Model written by Ijsselstein R. R. and published by . This book was released on 1985 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Modeling of Shock-sensitivity Experiments by :
Download or read book Numerical Modeling of Shock-sensitivity Experiments written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Forest Fire rate model of shock initiation of heterogeneous explosives has been used to study several experiments commonly performed to measure the sensitivity of explosives to shock and to study initiation by explosive-formed jets. The minimum priming charge test, the gap test, the shotgun test, sympathetic detonation, and jet initiation have been modeled numerically using the Forest Fire rate in the reactive hydrodynamic codes SIN and 2DE.
Book Synopsis Numerical Modeling of Explosives and Propellants by : Charles L. Mader
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.
Book Synopsis Numerical Study of Detonation Flame Arrestor Performance and Detonation Interaction with the Arrestor Element by : Hoden Ali Farah
Download or read book Numerical Study of Detonation Flame Arrestor Performance and Detonation Interaction with the Arrestor Element written by Hoden Ali Farah and published by . This book was released on 2020 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical study of detonation propagation and interaction with a flame arrestor product in a combustible gas/vapor transport pipeline system is conducted. The flame arrestor element is modeled as a porous medium using the Forchheimer equation, which is incorporated in the governing conservation equations as a momentum sink. The Forchheimer porous medium model is then used to model the flow through a representative four-inch detonation flame arrestor and is validated with experimental data. The detonation propagation simulation is modeled with the Reynolds averaged Navier-Stokes (RANS) equations extended for reacting flows. A 21-step chemical kinetic mechanism with 10 species is used to resolve the hydrogen-oxygen combustion. A series of detonation propagation case studies is conducted to validate the numerical model. The detonation propagation numerical result is qualitatively compared to experimental data and is shown to have the same trend. Numerical simulation is used to predict the transmission or interruption of detonation wave propagation through the flame arrestor product and is confirmed with historical test data.
Book Synopsis Models of CJ Deflagrations and Their Transition to Detonations from the Interaction of a Detonation Wave with a Perforated Plate by : Wentian Wang
Download or read book Models of CJ Deflagrations and Their Transition to Detonations from the Interaction of a Detonation Wave with a Perforated Plate written by Wentian Wang and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The last stage of a deflagration-to-detonation transition (DDT) process involves the propagation and acceleration of a fast flame. This process is currently poorly understood. The difficulties lie in its complex structure, which is turbulent and involves multi-dimensional gasdynamic phenomena. Previous experimental studies have established these fast flames from the interaction of a detonation wave with a row of obstacles or porous plate. Two main questions remain unsolved: 1) What is the propagation speed of the fast flame obtained in these configurations and 2), Which factors dominate the occurrence of the DDT phenomenon? To answer these questions, two models have been constructed in the present work. Firstly, a quasi-1D gasdynamic model is proposed for estimating the transmitted reaction front speed and the strength of the transmitted shock. By alternately assuming a Chapman-Jouguet (CJ) deflagration or an inert shock, the model estimated the transmitted shock speeds. The comparison with extensive experimental data for a range of hydrocarbon fast flames revealed that the burning velocity required for transition to detonation was the CJ value. Secondly, a numerical shock-induced ignition model, which can impose mechanical fluctuations from a driven piston, was established in order to investigate the ignition and acceleration process, thereby clarifying the other question of interest. The results from the simulations indicated that the mechanical fluctuations can play an important role in triggering DDT by means of promoting the local ignition and amplification of the reaction front stemming from such ignition. It was also found that the maximum amplification effects occur with a fluctuation period between the non-fluctuated ignition delay and the time scale of chemical energy deposition. The inert simulation results show that two types of gasdynamic effects from the fluctuations were vital to the hot-spot formation. These hot spots make significant contribution to the detonation initiation.
Book Synopsis Numerical Modeling of Insensitive High-explosives Initiation by :
Download or read book Numerical Modeling of Insensitive High-explosives Initiation written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The initiation of propagating, diverging detonation is usually accomplished by small conventional initiators. As the explosive to be initiated becomes more shock insensitive, the initators must have larger diameters to be effective. Very shock-insensitive explosives have required initiators larger than 2.5 cm. We have numerically examined the process of initiation of propagating detonation as a function of the shock sensitivity of the explosive using the two-dimensional Lagrangian reactive hydrodynamic code 2DL and the Forest Fire rate to describe the shock initiation process of heterogeneous explosives. The initiation of propagating detonation in shock-insenstive explosives containing triamino trinitrobenzene results in large regions of partially decomposed explosive even when initiated by large initiators. The process has been observed experimentally and reproduced numerically.
Book Synopsis Three Dimensional Modeling of Shock Initiation of Heterogeneous Explosives by :
Download or read book Three Dimensional Modeling of Shock Initiation of Heterogeneous Explosives written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The basic processes in the shock initiation of heterogeneous explosives have been investigated theoretically using a model of a cube of nitromethane containing 91 cubic air holes. The interaction of a shock wave with the density discontinuities, the resulting hot spot formation and interaction, and the buildup to propagating detonation were computed using three-dimensional numerical Eulerian hydrodynamics with Arrhenius chemical reaction and accurate equations of state. The basic process in the desensitization of a heterogeneous explosive by preshocking with a shock pressure too low to cause propagating detonation was numerically modeled.
Book Synopsis Proceedings, Seventh Symposium (International) on Detonation by :
Download or read book Proceedings, Seventh Symposium (International) on Detonation written by and published by . This book was released on 1982 with total page 1120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Initiation of Propagating Detonations by :
Download or read book Initiation of Propagating Detonations written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The initiation of propagating detonation in PBS 9404, PBX 9502, and X0219 by hemispheric intiators of PBX 9404, 1.8 g/cm3-TATB, and X0351 is described numerically, using the two-dimensional Lagrangian code, 2DL, and the Forest Fire rate to describe the heterogeneous explosive shock initiation process. The initiation of propagating detonation in the insensitive explosive PBX 9502 by triple-shock-wave interaction from three initiators has been modeled using the three-dimensional, reactive, Eulerian hydrodynamicd code, 3DE.
Download or read book Proceedings written by and published by . This book was released on 1982 with total page 1126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Simulations of Detonation Re-initiation Behind an Obstacle by : Lau-Chapdelaine
Download or read book Numerical Simulations of Detonation Re-initiation Behind an Obstacle written by Lau-Chapdelaine and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This numerical study explored the mechanisms responsible for the re-initiation of a detonation, which quenched while diffracting over a half-cylinder obstacle. Its purpose was to accurately predict when detonation re-initiations occur, determine roles of re-initiation mechanisms, and compare effects of chemical models. The model used reactive Euler equations with the one-step Arrhenius or two-step chain-branching chemical models, calibrated to post-shock conditions to reproduce the ignition delay. Simulations were validated using the stoichiometric methane-oxygen experiments of Bhattacharjee et al.. The model accurately predicted detonation re-initiation conditions found in experiments with good qualitative and quantitative agreement. While the one-step model was sufficient in predicting re-initiation, the two-step model reproduced finer details. Kelvin-Helmholtz and Richtmyer-Meshkov instabilities did not appear to influence detonation re-initiation of the Mach stem. Detonation re-initiation occurred due to adiabatic compression of the Mach stem, or transport of a flame along the wall jet. Transverse detonations were poorly reproduced.
Book Synopsis Theoretical and Numerical Combustion by : Thierry Poinsot
Download or read book Theoretical and Numerical Combustion written by Thierry Poinsot and published by R.T. Edwards, Inc.. This book was released on 2005 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introducing numerical techniques for combustion, this textbook describes both laminar and turbulent flames, addresses the problem of flame-wall interaction, and presents a series of theoretical tools used to study the coupling phenomena between combustion and acoustics. The second edition incorporates recent advances in unsteady simulation methods,
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