Bulletin of the American Physical Society
15th APS Topical Conference on Shock Compression of Condensed Matter
Volume 52, Number 8
Sunday–Friday, June 24–29, 2007; Kohala Coast, Hawaii
Session P7: Detonation Shock Dynamics |
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Chair: Larry Hill, Los Alamos National Laboratory Room: Fairmont Orchid Hotel Promenade III |
Thursday, June 28, 2007 10:30AM - 10:45AM |
P7.00001: Detonation Shock Dynamics Calibration of PBX 9501 Tariq Aslam Detonation shock dynamics (DSD) has proven to be a fast and accurate alternative to direct numerical simulation of propagating detonations. Here, the requisite differential equations, experimental data and calibration procedure will be outlined for the plastic bonded explosive PBX 9501. It will be shown that the DSD model can fit the existing PBX 9501 data to within the experimental uncertainty. [Preview Abstract] |
Thursday, June 28, 2007 10:45AM - 11:00AM |
P7.00002: Application of Detonation Shock Dynamics (DSD) on Youngs-Type Discontinuous Interface Geometry Toru Aida, John Walter Detonation Shock Dynamics (DSD) describes the evolution of two- or three-dimentional detonation wave by assuming that the detonation reaction zone is significantly small and that the curvature of the detonation wave front is also small with respect to the explosive in question. The current DSD solver obtains its input parameters by superimposing (normally rectangular Cartesian) grid points over the high explosive regions, determining signed distances from each grid point to the HE boundaries (+: inside of HE; -: outside) and assigning material identification to each grid point based on its location within the system. It has been shown to work with Lagrangian mesh where mesh entities, particularly cell faces, are contiguous and therefore, distances to material interfaces, namely HE and other materials and/or external boundaries, are precisely defined. In this paper a new scheme of DSD driver code to allow the material interfaces to be expressed in a discontinuous manner, such as Youngs material interface construction for 3D Eulerian hydrodynamics code. [Preview Abstract] |
Thursday, June 28, 2007 11:00AM - 11:15AM |
P7.00003: An extension of detonation shock dynamics for insensitive explosives Mark Short, John Bdzil, Tariq Aslam Resolved, direct numerical simulations of the detonation of high explosives (HE) in geometries of engineering interest are largely unattainable due to the scale disparity between the shorter detonation reaction-zone length and the longer characteristic explosive charge dimension. However, multi-scale mathematical modeling, utilizing this scale disparity, has led to the development of the theory of detonation shock dynamics (or DSD). With DSD, the propagation of a detonation in a HE configuration is described by a surface evolution equation for the detonation front. For insensitive high explosives (IHE), detonations typically have two characteristic reaction stages: a fast reaction where the majority of the heat of reaction is released, followed by a second significantly slower reaction (e.g. through carbon coagulation in PBX-9502). We show that the presence of this slowly reacting, weak heat release zone can have a significant (time-dependent) influence on the evolution of a detonation in IHE. We also describe an extension to the DSD concept, specifically tailored to detonations, in IHE which treats fast-slow chemistry models. The fast chemistry is handled with a DSD front rationally coupled to a distributed, resolved (reactive burn) model for handling the slow chemistry step. [Preview Abstract] |
Thursday, June 28, 2007 11:15AM - 11:30AM |
P7.00004: Detonation propagation in high explosives Linhbao Tran Detonation wave modeled as a Chapman-Jouguet detonation using a hydrodynamic burn is investigated. Detonation front is represented by a level-set function and its propagating velocity is calculated through the Hugoniot jump conditions in local shock coordinate. Conservation laws are solved for both gas and solid phase with full coupling applied at material interfaces. Boundary conditions at free surfaces as well as solid surfaces are accurately handled. Validation is performed for a PBX-9501 cylinder. Simulation of detonation propagating through a bed of Aluminum particles show a complex flow field behind the detonation with multiple shock-shock interactions, as well as a slowed down detonation wave. Corner turning problem is also performed and compared with other numerical and experimental results. [Preview Abstract] |
Thursday, June 28, 2007 11:30AM - 11:45AM |
P7.00005: Critical Ignition Transients in Condensed Explosives D. Scott Stewart, Sunhee Yoo, David E. Lambert Comparisons of the motion of a detonation shock measured in experiment, that predicted by the asymptotic theory of detonation shock dynamic (DSD-theory) that include shock acceleration, and direct multi-material simulation are made. A non-ideal, reactive equation of state and a rate law is used to describe the explosive and was employed in both the theoretical (DSD) calculations and the multi-material simulations. The experiment, theory are found to be in excellent agreement and this indicates that for a large class of important detonation flows one can use the DSD model. DSD assumes that the detonation shock propagates along its normal direction with its speed determined by its total shock curvature (D-kappa). We present a calculation of critical energies and initial conditions needed to light the explosive using theory and show comparison with experiments conducted by Lambert in HMX-based explosives. [Preview Abstract] |
Thursday, June 28, 2007 11:45AM - 12:00PM |
P7.00006: Detonation Failure in Ideal and Non-Ideal Explosives P.J. Haskins, M.D. Cook In this paper we revisit and extend the classic treatment of detonation failure developed by Eyring et. al. [1]. We recently published a development of this theory [2] in which a pressure dependant rate law was substituted for the Arrhenius temperature dependant law originally considered. Here we show that by assuming a 2-component rate law based upon a temperature dependant ignition phase and a pressure dependant growth phase we are able to rationalise the very different failure characteristics (critical diameter and velocity decrement at failure) of ideal and non-ideal explosives. \newline \newline [1] Eyring, H., Powell, R.E., Duffy, G.H., and Parlin, R.B., ``The stability of detonation,'' Chem. Rev. 45, 69-181 (1949). \newline [2] Haskins, P.J., Cook, M.D., and Wood, A.D., ``On the dependence of critical diameter and velocity decrement at failure on the burn law,'' in proceedings of the 33rd International Pyrotechnics Seminar, Fort Collins, Co, USA, 385-391 (2006). [Preview Abstract] |
Thursday, June 28, 2007 12:00PM - 12:15PM |
P7.00007: Physical Model of Low Velocity Detonation in Plasticized HMX. Konstantin Grebenkin, Michail Taranik, Svetlana Tsarenkova, Alexander Shnitko Phenomenon of low velocity detonation (LVD) is known many years, but its physical mechanism has not been understood in details, yet. A physical model of LVD is presented in the given report. The main idea of the model is that LVD in dense plasticized explosives may take place only when due to the lateral unloading the pressure at the leading shock front is reduced as compared to that at normal detonation (ND). As a result, the chemical reaction rate and, hence, the energy released between the leading shock front and the sound surface must be lesser as compared to that at ND. But, from other side, this may be enough to sustain the stationary regime of the LVD propagation. The model has been implemented in 2-D hydrocode and verified by means of computer modeling of the experiments (Leuret e.a., 1998) where LVD was observed in plasticized HMX. The results of our calculations supports the suggestion that LVD wave in plasticized HMX is a complex of the leading shock wave having pressure near 1 GPa and the compression wave following the front. Stationary propagation of such structure is possible only when some specific combination of the energy release rate and the lateral unloading intensity takes place. [Preview Abstract] |
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