Bulletin of the American Physical Society
2005 14th APS Topical Conference on Shock Compression of Condensed Matter
Sunday–Friday, July 31–August 5 2005; Baltimore, MD
Session L2: Detonations & Shock-Induced Chemistry IV |
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Chair: Larry Hill, Los Alamos National Laboratory Room: Hyatt Regency Constellation C |
Tuesday, August 2, 2005 3:30PM - 4:00PM |
L2.00001: Direct Numerical Simulation of Detonation Invited Speaker: The last decade has been witness to a thousand fold gain in computational power, in addition to comparable gains from improved computational algorithms such as adaptive mesh refinement algorithms. But, even with these gains, there are many detonation phenomena which are beyond the current and foreseeable capabilities of simulation. Some of the key issues are 1) lack of high rates of convergence for shock capturing schemes 2) Multi-scale nature of detonation and 3) Poorly posed mathematical models. An overview of accomplishments in the field, current state of the art, and future work on detonation simulation will be discussed. [Preview Abstract] |
Tuesday, August 2, 2005 4:00PM - 4:15PM |
L2.00002: Detonation Reaction Zones in Condensed Explosives Craig Tarver Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich -- von Neumann -- Doring (NEZND) theory and reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes is discussed for nitromethane, HMX, TATB and PETN. Progress in measuring and modeling the complex three-dimensional structural of these detonation waves is also discussed. This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48. [Preview Abstract] |
Tuesday, August 2, 2005 4:15PM - 4:30PM |
L2.00003: Detonation Wave Profile in PBX-9501 Ralph Menikoff Measurements of a CJ-detonation wave in PBX-9501 with a VISAR technique have shown a classical ZND profile for the reaction zone. This is compatible with one-dimensional simulations using realistic equations of state and an Arrhenius reaction rate fit to available data from other experiments. Moreover, the reaction zone width is less than the average grain size in the PBX. In contrast to initiation, which requires hot spots, the reaction rate from the bulk shock temperature is sufficiently high for propagating a detonation wave. This raises questions with burn models used for both ignition and propagation of detonation waves. [Preview Abstract] |
Tuesday, August 2, 2005 4:30PM - 4:45PM |
L2.00004: The physical background of a new detonation model Alain Froger We previously described /1/ a detonation model suitable to simulate highly transient evolutions such as SDT or detonation failure. This model involves a special thermodynamical description on the mixture in the reaction zone. It requires neither additional sub-models like celerity/curvature relationship nor special equations of state for the mixture. In this paper, we emphasize the physical background of the model. By applying mechanics and thermodynamics laws in the reaction zone, we proved that the energy of detonation is not a physical constant but is depending on the local thermodynamical state. We also showed that an equation of state cannot be defined for the mixture in the reaction zone. These two points are the fundamentals of the model. Moreover we derived important energy relationshis that explain i) how the detonation failure occurs, ii) why the possible detonation celerity is restricted between D$_{CJ}$ and roughly 0.9D$_{CJ }$for high explosives and iii) why insensitive explosives are high explosives. \newline \newline 1- A. Froger ``A reaction zone enthalpy balance model to simulate shock-to-detonation transition and unsteady wave propagation'' 2003 APS-SCCM conference (Portland, OR,USA, July 20-25 2003) [Preview Abstract] |
Tuesday, August 2, 2005 4:45PM - 5:00PM |
L2.00005: Toward a New Paradigm for Reactive Flow Modeling Bob Schmitt Traditional reactive flow modeling provides a computational representation of shock initiation of energetic materials. Most reactive flow models require ad hoc assumptions to obtain robust simulations. These assumptions result from partitioning energy and volume change between constituents in a reactive mixture. These models assume pressure and/or temperature equilibrium for the mixture. Many mechanical insults to energetic materials violate these assumptions. Careful analysis is required to ensure that the model assumptions and limitations are not exceeded. One limitation is that SDT is replicated only for strong planar shocks. These models may require different parameters to match data from thin pulse, ramp wave, or multidimensional loading. This approach fails for complex loading. To accurately simulate reaction under non-planar shock impact scenarios a new formalism is required. The continuum mixture theory developed by Baer and Nunziato is used to eliminate ad hoc assumptions and limitations of current reactive flow models. This modeling paradigm represents the multiphase nature of reacting condensed/gas mixtures. Comparisons between simulations and data are presented. [Preview Abstract] |
Tuesday, August 2, 2005 5:00PM - 5:15PM |
L2.00006: Steady 2d Detonations and the DSD Theory Sergey N. Lubyatinsky, B.G. Loboiko, V.P. Filin, O.V. Kostitsyn, E.B. Smirnov The simplest Detonation Shock Dynamics (DSD) theory assumes that the detonation normal velocity D is determined by the total front curvature k and that the edge angle, the angle between the normal to the front and the explosive edge, has a unique value for each explosive and confinement material combination. This model has been used to derive the ordinary differential equations describing steady 2D detonation front shapes in slab, cylinder and rib geometries. It was found that one solution (a steady detonation front shape) corresponds to several combinations of the confinement material and the defining charge dimension (slab thickness, cylinder radius, or inner rib radius). Comparing experimental data for these combinations and analyzing the shape difference at the edge provide valuable information on the D(k) relation at low D corresponding to forced detonation regimes. The analysis of the experimental data on IHE ribs detonation indicates that as D decreases k tends to a limit of about 0.05 1/mm, i.e., of the order of reciprocal critical diameter. This revises the present view of the D(k) relation making the DSD theory consistent with the experimentally observed critical diameter. [Preview Abstract] |
Tuesday, August 2, 2005 5:15PM - 5:30PM |
L2.00007: Thermodynamic Simulating the Detonation Properties of CNO--Explosives Sergey Victorov, Sergey Gubin, Irina Maklashova, Vitaly Pepekin In this work we predict the detonation characteristics of recently synthesized hydrogen-free high explosives containing C, N, and O atoms. This is heterocycles (nitrofurazans and nitrofuroxans) and a few other new explosives. Their initial densities and heats of formation are high and, consequently, their detonation parameters are expected to be high as well. This reason and the lack of the corresponding experimental data due to just small amounts of the synthesized matter motivate great practical interest in realistic predicting the detonation properties of these explosives. The detonation characteristics are computed with the TDS code for both new hydrogen-free explosives and a few explosive mixtures based on them. A thermodynamically consistent model is used for the solid and liquid nanoparticles of graphite and diamond. The heats of detonation and the performances of these explosive systems are calculated as well. The calculations show that the detonation parameters of the investigated explosives and explosive mixtures are very high. Furthermore, the predicted results of the metal plate test are high for these explosive systems and, hence, their performance is high. The results of this work allow us to conclude that the development of new hydrogen-free both individual explosives and explosive mixtures has considerable promise. [Preview Abstract] |
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