Download or read book Detonation Initiation by Annular Jets and Shock Waves written by and published by . This book was released on 2005 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project was an experimental test of the concept of initiating detonations in PDEs with imploding shock waves. The existing 6-inch shock tube at Caltech was used to create hot, high pressure air behind a reflected shock wave. The hot air created an imploding annular shock wave when it jetted through an annular orifice into a 76 mm diameter, 1 m long tube attached to the end of the shock tube. The test tube was filled with either stoichiometric ethylene-oxygen or propane-oxygen diluted with nitrogen. Piezoelectric pressure transducers and ionization gauges were used to determine the type of combustion event initiated by the annular jet of hot air. The stagnation conditions in the shock tube and the amount of dilution with nitrogen in the test section were varied to find the critical conditions for the onset of detonation in each test mixture. Less sensitive (high dilution) mixtures required larger stagnation pressures in order to initiate a detonation. We were unable to initiate either ethylene or propane-air mixtures within our facility limits. Extrapolation of the low-dilution data indicates that very high stagnation pressures (> 16 bar) are required.
Download or read book Detonation Initiation in a Hot Jet and by Colliding Fragments written by Egil Borse and published by . This book was released on 1978 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This report describes three phases with experimental observations and theoretical evaluations related to the initiation of detonation in a hot jet caused by the jet itself or by colliding fragments. The report is based upon an evaluation of accidental explosions where initiations of detonations in actual past accidents seem to be connected with the existence of a local constant volume combustion process inside a vapour cloud. There exist two plausible mechanisms for the initiation of detonation -- one is based upon the existence of a radical gradient in a hot jet, which during the initiation process amplifies the process by e.g. the SWACER mechanism through a critical length or volume until a self-sustained detonation wave is formed. -- the other mechanism is that a constant volume combustion (which produces the hot jet) causes metal to fragment and that the collisions between fragments or a wall produces a shock wave strong enough to initiate a detonation. Phase 1 and 2 of this report show that the first mechanism needs one additional factor: either a large scale vortex (phase 2) or the production of a Mach-Stem by merging two or more "low strength" shocks (phase 1). Phase 1 shows through streak and single spark Schlieren photography the most common mechanisms of detonation initiation. Phase 1 also gives additional evidence of the quenching characteristics of a detonation wave. Phase 2 gives evidence of the increased flame velocity in a hot jet and the formation of vortices by use of single spark Schlieren photography and pressure readings. The results from phase 2 indicate that the production of vortices is only secondary in the initiation of detonation in a hot jet; the vortices must only be of a particular size. The discussion in phase 1 shows that the production of Mach-Stem by merging two or more "low strength" shocks might be the prime mechanism of initiation in addition to a mechanism which could well be the SWACER mechanism. Phase 3 shows that detonation initiation caused by colliding fragments might be possible and is a more plausible explanation of past accidents involving initiation of detonation than the above mechanisms. That the pressure build-up is close to the natural frequency of diaphragm seems to be a necessary condition for initiation of detonation in the experimental apparatus used in phase 3. This might explain why detonation initiation in accidental gas explosions only occurs in relation to a constant volume combustion (explosion), but even then, only occasionally. A final theory of detonation initiation by e.g. a static electric discharge initiation a series of vortices building up a system of wavelets, is suggested. The wavelets discussed in phase 1 and the turbulence discussed as secondary to the wavelets in phase 2 might then form a process which is similar to the Swacer mechanism in theory, but not in the physics. There is no final evidence whether this process also is acting in phase 3, with or without help from the fragmentation. A static electric discharge might compete with the fragmentation theory in phase 3, or the shock reflection theory in phase 1, in explaining past accidents
Download or read book Shock Waves Science and Technology Library Vol 6 written by F. Zhang and published by Springer Science & Business Media. This book was released on 2012-03-28 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Generating Detonation Waves in an Annulus Via Phased Adiabatic Shocks written by Joseph D. Heath and published by . This book was released on 2015 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis documents the design and development of a continuous rotating detonation combustor. The design of the combustor incorporates a new system to initiate and control detonation waves within an annular duct. This system known as the wave controller functions by generating phased adiabatic shocks using an azimuthal array of spark plugs. The main intent of the research was to determine the effectiveness and usability of the wave controller in developing transverse waves to initiate a detonation wave. Imaging data of the adiabatic shocks in the annulus was obtained using a high-speed camera and optical setup. The data presented here illustrates the wave controller's capability in creating transverse shock waves traveling circumferentially. Another aspect of the research is to introduce a new injection scheme and provide experimental results on its effectiveness in mixing fuel and oxidizer.
Download or read book Toward Detonation Theory written by Anatoly N. Dremin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is known that the Chapman-Jouguet theory of detonation is based on the assumption of an instantaneous and complete transformation of explosives into detonation products in the wave front. Therefore, one should not expect from the theory any interpretations of the detonation limits, such as shock initiation of det onation and kinetic instability and propagation (failure diameter). The Zeldovich-Von Neuman-Doring (ZND) theory of detonation appeared, in fact, as a response to the need for a theory capable of interpreting such limits, and the ZND detonation theory gave qualitative interpretations to the detonation limits. These interpretations were based essentially on the theoretical notion that the mechanism of explosives transformation at detonation is a combustion of a layer of finite thickness of shock-compressed explosive behind the wave shock front with the velocity of the front. However, some experimental findings turned out to be inconsistent with the the ory. A very small change of homogeneous (liquid) explosives detonation velocity with explosive charge diameter near the rather sizable failure diameter is one of the findings. The elucidation of the nature of this finding has led to the discovery of a new phenomenon. This phenomenon has come to be known as the breakdown (BD) of the explosive self-ignition behind the front of shock waves under the effect of rarefaction waves.
Download or read book Dynamics of Detonations and Explosions written by and published by AIAA. This book was released on 1991 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Excitation of Detonation by Shock Waves Selected Portions written by A. S. Derzhavets and published by . This book was released on 1972 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current theoretical views on the mechanism of excitation of detonation are first discussed. Excitation by shock waves is then treated at length. The effects of various parameters, such as shock wave velocity, temperature, pressure, duration of action, distance and dimensions of passive charge, etc., on initiation of detonation are considered, and appropriate formulas and relations are given. The impulse initiation of detonation of explosives is characterized by 3 phases; shock wave initiation of chemical reactions, growth of this reaction in the solid explosive, and appearance of the detonation wave.
Download or read book Dynamics of Shock Waves Explosions and Detonations written by J. Raymond Bowen and published by . This book was released on 1984 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2008 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings written by and published by . This book was released on 1989 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers presented in this publication cover special problems in the field of energetic materials, particularly detonation phenomena in solids and liquids. General subject areas include shock-to-detonation transition, time resolved chemistry, initiation modeling, deflagration-to-detonation transition, equation of state and equation of state and performance, composites and emulsions, and composites and emulsions/underwater explosives, reaction zone, detonation wave propagation, hot spots, detonation products, chemistry and compositions, and special initiation.
Download or read book 40th AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit July 11 14 2004 Fort Lauderdale FL 04 3900 04 3949 written by and published by . This book was released on 2004 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 39th AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit July 20 23 2003 Huntsville Alabama no 4799 written by and published by . This book was released on 2003 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Investigation of the Initiation of Detonation Behind a Reflected Shock Wave written by Thomas John Krusic and published by . This book was released on 1966 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this work was to develop an experimental apparatus for the study of the initiation of detonation in a gaseous medium as a result of shock compression. The design of the apparatus is described, and results of some preliminary experiments are reported. They indicate that the mechanism of the initiation process behind reflected waves in a shock tube is essentially different than that caused by an accelerating flame. (Author).
Download or read book Initiation of detonation resulting from a collision of a shock wave with obstacles written by C. K. Chan and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Initiation of Detonation in Composition B by an Underwater Shock Wave written by Michael Chung and published by . This book was released on 1996 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies on Shock Wave Initiation of Gaseous Detonation written by Edward Forbes Greene and published by . This book was released on 1949 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Initiation of Detonation by Non ideal Blast Waves written by Robert John Cesarone and published by . This book was released on 1977 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is a theoretical investigation of the initiation of detonation by nonideal blast waves. The study used the output of the CLOUD program as the source of flow data for blast waves generated by bursting spheres. Each cell that surrounds the bursting sphere is assumed to be reactive with an Arrhenius type kinetic rate law over a temperature range of from 1000 - 2700 K. Outside this range the cell is assumed to be nonreactive. In the technique the delay to explosion is integrated numerically from the time of shock passage over that cell until the temperature of the cell drops below 1000 K.A minimum of this summation time was found for cells either near the bursting sphere or right at the edge of the sphere. Conceptually, as the bursting sphere is made larger and larger one eventually reaches a point at which the delay time to explosion in at least one of the cells is long enough such that an explosion process can start. This is taken as the criterion for detonation initiation in this model. Numerous cases were run and initiation behavior was plotted both as a function of the total energy of the bursting sphere and the energy density of the bursting sphere. In addition, a few runs were made for the ramp edition of energy to compare to the bursting sphere results. The study shows that as the energy density of the sphere gas becomes lower the total energy required for initiation increases sharply. This is in agreement with experimental studies using spark initiation.
