Download or read book Effects of Granular Propellant Fracture on the Transition from Deflagration to Detonation written by Yang Tao and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deflagration to detonation Transition in Granular Double base Propellant written by Jason D. Rogers and published by . This book was released on 2012 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deflagrationo Detonation Transition in HMX Based Propellants written by M. Cowperthwaite and published by . This book was released on 1978 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research on the deflagration-to-detonation transition (DDT) is important to the Air Force because many of the energetic propellants required for present and future long-range delivery systems are explosively filled compositions that are capable of undergoing DDT. HMX-based propellant, for example, usually burns reliably in rocket motors but has detonated and destroyed the motor on several occasions. Possible steps leading to detonation in the rocket motor are fracture of propellant ahead of the flame and the subsequent formation of shock waves produced by the increased burning rate of fractured propellant. But even in this case, the mechanism of DDT and the conditions for its initiation are not adequately understood. The long-range objective of the present research program is to develop a computational capability for assessing the DDT hazard in explosively filled propellants. The program is based on the concept that a basic understanding of the physical and chemical processes involved in DDT is necessary to achieve this objective. Combined theoretical and experimental studies to determine the pressure fields behind and ahead of the flame and to establish mechanisms of DDT are required to develop such understanding. (Author).
Download or read book Deflagration to Detonation Transition in Heteorogeneous Solids A Bibliography written by E. W. Price and published by . This book was released on 1980 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication contains a list of 341 references relating to the mechanism of transition to detonation in heterogeneous high energy solids, with particular reference to solid rocket propellants and granular propellant charges for guns. Because of the important role played by porosity, many of the references pertain to flow, flame spread and pressure rise in porous materials, and to the mechanics of formation cracks and propagation under dynamic loading. This partial list of references was developed primarily from lists contained in papers presented at the 1978 ONR/AFOSR Workshop on Deflagration-to-Detonation Transition (CPIA Publication 229, September 1978), and from reports received subsequent to that Workshop. A subject coding was developed and used to classify each reference. (Author).
Download or read book Raising the Flag of Truth written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluid Mechanical Processes of Deflagration to Detonation Transition in Beds of Porous Reactive Solids written by Stephen James Hoffman and published by . This book was released on 1980 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fluid mechanical processes which characterize a transition from deflagration to detonation in granular beds of solid propellant have not at present been sufficiently refined to allow accurate modelling of the phenomenon. In an attempt to improve this situation, this report has investigated what might be considered basic mechanisms and consequences that arise from a set of assumptions for the governing and constitutive equations which take into account the two phase nature of this problem. A qualitative description of the flow process is made, based on observations obtained from DDT experiments. From this, certain conclusions are reached as to the properties needed by propellants to exhibit a deflagration to detonation transition (DDT). The numerical integration scheme itself is examined in detail in order to further understand the consequences of its use.
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 Initiation Combustion and Transition to Detonation in Homogeneous and Heterogeneous Reactive Mixtures A Summary written by and published by . This book was released on 1981 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Certain aspects of ignition source effects in reactive fuel-air mixtures are discussed. These aspects include effects of chemical sensitizers, flame acceleration, flame area, and ignition point location. The other area involves the hydrodynamic modeling of ignition and flamespreading in granular energetic solids to predict the potential for deflagration-to-detonation transition (DDT). Key results in the first area are that chemically sensitized clouds can lead to detonation, that flame acceleration or a large increase in the time rate of increase of the flame area are needed for transition from deflagration to detonation and that it is very difficult to generate damaging overpressure from edge-ignited combustion even for very high subsonic burning velocities. The research dealing with analysis of DDT in porous high energy solid propellant has shown (for the first time) actual steady-state detonation solutions, following the unsteady flow, for materials with sufficient porosity and critical burning rate properties. Limits of the run-up length to detonation are predicted as a function of propellant chemical energy, burning rate, bed porosity, and granulation (size). The detonation states conform to realistic measured conditions for porous HMX and RDX propellants.
Download or read book Deflagration to Shock to Detonation Transition of Energetic Propellants written by H. Krier and published by . This book was released on 1984 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is well known that explosive-based propellants are susceptible to detonation from the controlled deflagration mode of combustion. In some instances a confined zone of granulated propellant adjacent to a zone of cast propellant can provide a rapid enough pressure-rise rate to shock initiate the cast material. If the cast propellant has voids, the detonation will initiate at some location ahead of the granulated bed/cast material interface. This report is a summary of the research activities that focus on the analysis and modeling of the physics of such highly transient flows.
Download or read book 30th AIAA ASME SAE ASEE Joint Propulsion Conference written by and published by . This book was released on 1994 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Deflagration to Detonation Transition in High energy Solid Propellants written by Patrick Barry Butler and published by . This book was released on 1984 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 910 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Deflagration to Detonation Transition of Gun and Small Arms Propellants written by and published by . This book was released on 1988 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the early 1970s at least 4 accidents have occurred in European countries in which propellants have burned to detonation, that is have undergone a transition from deflagration to detonation, all of which involved porous small arms propellants. This report reviews the findings of researchers in Finland, France, the Federal Republic of Germany, the Netherlands, Switzerland, the United Kingdom, and the United States who studied the potential of a variety of propellants to detonate under different confinement conditions. Details of work performed are given and information is included on tests used in the various studies and the results of those tests.
Download or read book Modeling of Convective Mode Combustion Through Granulated Propellant to Predict Transition to Detonation written by Herman Krier and published by . This book was released on 1977 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Derivation of the two-phase (reactive particle) unsteady-flow conservation equations are presented based upon the generally accepted concept of separated-flow. The resulting formulation is compared with those equations derived by others, and questions are raised as the correctness or interpretation made by previous modelers. Details of the numerical method chosen to solve these equations (an explicit two-step MacCormack scheme) are also presented. Solutions are presented that predict the pressure wave build-up and accelerating ignition (flame) front for highly loaded beds of granulated solid propellant fixed in a rigid container. Some discussion is given of the sensitivity of these predictions as a function of the assumed constitutive relations for interphase heat and momentum transfer, for particle-particle resistance, and propellant burning rate functions. As yet no unambiguous criterion for deflagration-to-detonation transition (DDT) has been presented. (Author).
Download or read book Transition from Deflagration to Detonation in Granular Explosives written by Richard R. Bernecker and published by . This book was released on 1972 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deflagration to detonation transition (DDT) has been observed for 91/ 9 RDX/Wax over the range of 67 - 95% TMD. The initial process monitored was the propagation of a convective flame front through the porous charge. Some time after that a postconvective front was formed; it traveled at a greater speed and overtook the convective front. About 10 - 20 microseconds after this intersection and 10 - 20 mm beyond it, detonation appeared. Details of this proposed mechanism and their variation with compaction are fully described in the report. A few experiments at 70% TMD were also made on 97/3 and 94/6 RDX/ Wax and on ammonium picrate. Only the latter failed to undergo a transition to detonation in the apparatus used.
Download or read book Proceedings written by and published by . This book was released on 1989 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt:
