Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session K1: EM-7: Detonation |
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Chair: Ralph Menikoff, Los Alamos National Laboratory Room: Tennessee Ballroom C |
Tuesday, June 30, 2009 1:30PM - 1:45PM |
K1.00001: A Continuum Theory for Shock Induced Heating of Metalized Explosive Keith Gonthier, Sunada Chakravarthy, Chad Rumchik A well-developed continuum field theory for Deflagration-to-Detonation Transition (DDT) in granular explosive is generalized to account for the existence of an arbitrary number of condensed phases and a gas product phase. Formulation of the more generic theory is motivated by a desire to model both the low and high pressure impact response of metalized explosive for which the metal and explosive grains may have distinct average densities, velocities, temperatures, and sizes. The theory is consistent with the strong form of the dissipation inequality and allows for flexible partitioning of dissipation between phases. The theory is applied to inert impact of aluminized HMX in the limit of low gas pressure. Emphasis is placed on characterizing the spatial structure of planar deformation waves and its dependence on impact speed and initial metal mass fraction. [Preview Abstract] |
Tuesday, June 30, 2009 1:45PM - 2:00PM |
K1.00002: JAGUAR Procedures for Detonation Behavior of Explosives Containing Boron Leonard Stiel, Ernest Baker, Christos Capellos The JAGUAR product library was expanded to include boron and boron containing products. Relationships of the Murnaghan form for molar volumes and derived properties were implemented in JAGUAR. Available Hugoniot and static volumertic data were analyzed to obtain constants of the Murnaghan relationship for solid boron, boron oxide, boron nitride, boron carbide, and boric acid. Experimental melting points were also utilized with optimization procedures to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX - boron mixtures calculated with these relationships using JAGUAR are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that boron mixtures may exhibit eigenvalue detonation behavior, as observed by aluminized combined effects explosives, with higher detonation velocities than would be achieved by a classical Chapman-Jouguet detonation. Analyses of calorimetric measurements for RDX - boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the energy output obtained from the detonation of the formulation. [Preview Abstract] |
Tuesday, June 30, 2009 2:00PM - 2:30PM |
K1.00003: Steady non-ideal detonations Invited Speaker: Theories for determining the velocity of detonation (VoD) in highly non-ideal explosives, e.g. commercial explosives used in mining, are discussed. Such explosives have critical charge diameters of several centimetres. An analysis of the interaction between detonations and confining materials along the explosive-confiner interface reveals there a two main types of interaction. In the first (denoted here by case 1) the detonation drives an oblique shock into the confiner. For the second (case 2), a wave propagates in the confiner ahead of the detonation in the explosive. Shock polar interactions are examined for commercial explosives and rocks, which shows that a significant proportion of problems are case 2 in mining. For case 1, numerical simulations show that for a given explosive model there is a unique relationship (valid for all charge diameters and confinements) between the VoD and the curvature of the detonation shock at the charge axis. This relationship is shown to be well predicted by a quasi-one-dimensional type analysis. A simple detonation shock dynamics method which uses this relationships predicts well the VoD even in highly non-ideal cases, provided the explosive is sufficiently confined (usually the case in mining), but which is inaccurate in the limit of an unconfined charge. Preliminary results of a novel variational method for solving the unconfined situation are also discussed. Numerical simulations are performed to investigate the coupling mechanisms in case 2 situations, including the influence on diameter effects. It is shown that, in agreement with an approximate theory, the detonation is driven up to VoDs above the confiner's sound speed, and the wave in the confiner weakly pre-compresses the explosive ahead of the detonation front. [Preview Abstract] |
Tuesday, June 30, 2009 2:30PM - 2:45PM |
K1.00004: Incorporation of a Chemical Kinetics Model for Composition B in a Parallel Finite-Element Algorithm Elizabeth Kallman, Denise Pauler A thermal degradation model for Composition B (Comp B) explosive is being evaluated for incorporation into a finite-element algorithm [1]. The RDX component of Comp B dominates the thermal degradation since its decomposition process occurs at lower temperatures than TNT. The model assumes that solid and liquid RDX decompose by the same mechanisms, but along different reaction pathways [2, 3]. A steady-state approximation is applied to the gaseous intermediates and is compared to the full transient analysis for the entire reaction scheme. The parallel finite-element algorithm is used to predict the pressure increase on the interior of the metal casing of confined Comp B due to the production of gases during thermal decomposition. \\ \parindent=0pt \textbf{References} [1] E. M. Kallman, ``Scalable Cluster-Based Galerkin Analysis for Kinetics Models of Energetic Materials,'' SIAM CSE, March 2-6, 2009. [2] D. K. Zerkle, ``Composition B Decomposition and Ignition Model,'' 13th International Detonation Symposium, July 23-28, 2006. [3] J. M. Zucker, A. J. Barra, D. K. Zerkle, M. J. Kaneshige and P. M. Dickson, ``Thermal Decomposition Models for High Explosive Compositions,'' 14th APS Topical Conference on Shock Compression of Condensed Matter, July 31-August 5, 2005. [Preview Abstract] |
Tuesday, June 30, 2009 2:45PM - 3:00PM |
K1.00005: Reactive Burn Modelling at Temperature Extremes Using CREST Nicholas Whitworth The CREST reactive burn model uses entropy-dependent reaction rates to simulate behaviour in plastic bonded explosives. A CREST model for the TATB-based explosive PBX 9502, described at the last conference, was shown to be able to predict a range of shock initiation and detonation data at ambient temperature. However, it is well known that the behaviour of PBX 9502 varies significantly with initial temperature. Modelling the change in response that occurs upon heating or cooling the explosive, without having to modify the equation of state (EOS) and reaction rate parameters, is a significant challenge for reactive burn models. An important feature of CREST is that the initial state of the explosive can be incorporated without having to change the reference EOS or reaction rate model. In this paper, CREST is applied to PBX 9502 shock initiation data at temperature extremes. It is shown that the model can account for the variation in shock sensitivity with initial temperature using one set of parameters. [Preview Abstract] |
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