Bulletin of the American Physical Society
21st Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 64, Number 8
Sunday–Friday, June 16–21, 2019; Portland, Oregon
Session L1: DSIC: Detonation Modeling III |
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Chair: Scott Stewart, University of Florida Room: Grand Ballroom I |
Tuesday, June 18, 2019 4:00PM - 4:15PM |
L1.00001: Modeling the LANL Triple Point Overdrive Experiment in the FLAG Hydrocode Adam Coleman, Carl Johnson, Matt Biss A series of multi-point initiation (MPI) experiments investigating overdriven states in pentaerythritol tetranitrate (PETN) are currently underway at Los Alamos National Laboratory (LANL). These experiments make use of a three-initiator charge design that produces spherically diverging detonation waves that converge on axis producing a transient overdriven state in a PETN-acceptor charge. Acceptor thickness was varied (2.5 -- 10 mm) in a cutback series. Three-dimensional simulations were conducted using LANL's FLAG hydrocode in support of the MPI experiments. Simulations made use of the LANL developed MARS artificial viscosity and the AWSD reactive burn model. Results of the simulations were compared with experimental diagnostics (steak camera and photonic Doppler velocimetry). Detonation velocity as a function of acceptor thickness was calculated from the shock x-t profile and are compared with experimental calculations. The overdriven pressure profile in the acceptor charge was modeled to obtain a decay constant characterizing the relaxation to steady detonation behavior. The results of a mesh resolution study and the limitations of our current simulation are presented. Finally, scoping calculations of new experimental designs for future experiments at LANL are discussed. [Preview Abstract] |
Tuesday, June 18, 2019 4:15PM - 4:30PM |
L1.00002: Effects of Geometry on Line Wave Generator Breakout Profiles Containing XTX-8003 Bradley White, Robert Reeves, Michael Grapes, Craig Tarver, Denis Richard We performed computer simulations of Line Wave Generator (LWG) experiments containing the extrudable PETN-based explosive, XTX-8003, using the Ignition and Growth model in ALE3D. Parameters for the model were modified from a highly loaded PETN-based explosive and verified against run-to-distance measurements from shock initiation tests. The LWG experiments used 2 mm sized explosively filled channels with output channel center-to-center spacings of 7.5 mm with airgaps in between to prevent cross-talk between channels. Studies examined the effect of channel and airgap geometries on the simultaneity of the detonation wave front emanating from the channels into an output slab of a second explosive (Composition B). Planarity of the detonation front in the output slab at increasing depths was also studied. We will present results of these studies, as well as findings from interactions between multiple LWGs in a stacked configuration. This work was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-768420. [Preview Abstract] |
Tuesday, June 18, 2019 4:30PM - 4:45PM |
L1.00003: Hugoniot Properties of Explosives Forming Multi-Phase Condensed Species Leonard Stiel, Philip Samuels Analyses are conducted with the Jaguar thermochemical equilibrium program on the Hugoniot behavior of explosives which form multi-phase condensed species upon detonation, including carbon and aluminum, for wide ranges of temperatures and pressures. For carbon-forming explosives such as TNT, recently developed multi-phase property relationships with modified phase equilibrium behavior are utilized in the analyses. It is shown that discontinuities occur in the predicted Hugoniot curves because of the exhibited phase transitions. As noted previously, calculated shock velocities on the Hugoniots of carbon-forming explosives can exhibit double minima with respect to volume at which either, but not both, of the usual C-J point criteria that the detonation velocity is a minimum and the mass velocity is equal to the speed of sound are satisfied. At these conditions, the overall shock velocity minimum occurs at a limiting carbon phase transition point. With the sonic condition state considered as the C-J point, the other minimum point is on the overdriven Hugoniot with speeds of sound discontinuous and with shock velocities in this region lower than the C-J value. The indicated behavior is investigated by comparisons with experimental overdriven Hugoniot data, C-J velocities, sound speeds, and with cylinder test data using appropriate JWL relationships. [Preview Abstract] |
Tuesday, June 18, 2019 4:45PM - 5:00PM |
L1.00004: Study on the analog system of non-ideal detonation with two step chemical reaction model Yuanxiang Sun, Cheng Wang In this paper, the analog system is used to analyze the critical characteristics of non-ideal detonation and detonation instability: 1. The analog system of detonation with loss and the chemical reaction of two step reaction model is built, wherein an induction zone is followed by energy and heat release zone. Steady state of detonation wave structures are obtained by analytic method. By changing the value of the sensitivity exponent of reaction rate and the sensitivity coefficient of loss rate, the diagrams of steady detonation velocity and the loss coefficient under the corresponding parameter and detonation failure of linear boundary are obtained. And, the critical characteristics of detonation failure is obtained by theoretical analysis. 2. By the linear stability of the normal mode analysis, the spreading condition which limit the spread of the disturbance to the upstream is obtained. The stability of the steady state solution under the condition of the ideal and non-ideal (with loss) analog system of detonation is studied, and the influence of related parameters on the stability is analyzed. [Preview Abstract] |
Tuesday, June 18, 2019 5:00PM - 5:15PM |
L1.00005: Deep Learning for Energetic Material Detonation Performance Brian Barnes We present advances in accurate, extremely rapid prediction of detonation performance for energetic molecules. These models may be integrated into larger efforts for high-throughput virtual screening, molecular optimization, or an experimentalist’s selection of molecules before attempting a hazardous synthesis. Our machine learning workflow utilizes (a) a reference dataset generated from quantum mechanical calculations and the Cheetah thermochemical code, and (b) a message-passing neural network (MPNN) for nonlinear regression. The MPNN is a graph convolutional deep learning model best used with large datasets such as the one in this study. We create models to predict detonation velocity, detonation pressure, heat of formation, and density. Critically, prediction of the detonation properties requires absolutely no information other than the skeletal formula for a molecule. Molecules evaluated are CHNO-containing molecules from public datasets and known explosives. Neural net architecture and training are discussed. The MPNN is also evaluated against baseline models such as a feed-forward network, LASSO, random forest regression, and kernel ridge regression. The Python workflow for parallel, automated dataset generation and analysis is also discussed. [Preview Abstract] |
Tuesday, June 18, 2019 5:15PM - 5:30PM |
L1.00006: AWSD calibration for the HMX based explosives PBX 9501 and LX-07 Tariq Aslam, Matthew Price, Christopher Ticknor, Jeffery Leiding, Marvin Zocher A calibration of the AWSD reactive flow model, applied to the HMX based explosives PBX 9501 and LX-07, is presented. Requisite equation of state parameters for the high explosive reactants and products are based on a combination of experimental and theoretical data. The data needed to calibrate the reaction rate model, specifically shock to detonation transition and detonation propagation are presented along with model results. The length scales associated with reaction in the ZND-CJ limit as well as the sensitivity to initial temperature are discussed in the context of computational resolution requirements. [Preview Abstract] |
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