Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session L2: Detonations and Shock-Induced Chemistry III |
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Chair: Nicholas Whitworth, Atomic Weapons Establishment Room: Grand Ballroom IV-V |
Wednesday, June 29, 2011 9:15AM - 9:30AM |
L2.00001: Flash-gap Techniques for Imaging Front Curvature Detonation Records for Non-Ideal High Explosives Mark Short, Scott Jackson The light emission of high-temperature shocked inert gases in small gaps (a flash-gap) is a technique that has been utilized for measuring detonation time-of-arrival. In non-ideal granular explosives, air gaps between particles provide natural flash gaps that may be used for imaging of detonation front shape. We will present a series of tests on the use of flash-gap techniques for measuring detonation front shape, with application toward imaging in non-ideal high explosives. These include air and argon gaps, as well as salt and PETN flash-gaps. We will review other flash techniques from the literature and compare our results to them. [Preview Abstract] |
Wednesday, June 29, 2011 9:30AM - 9:45AM |
L2.00002: Burn Front and Reflected Shock Wave Visualization in an Inertially Confined Detonation of High Explosive Guillermo Terrones, Michael Burkett, Christopher Morris Proton radiography was used to investigate the spatiotemporal evolution of the burn front and associated reflected shocks on a PBX-9502 charge confined between an outer cylindrical steel liner and an inner elliptical tin liner. The charge was initiated with a line wave generator at 30 degrees from the major axis of the ellipse. This configuration provides a large region where the high explosive (HE) is not within the line of sight of the detonation line and thus offers a suitable experimental platform to test various burn models and EOS formulations. In addition, the off axis initiation allows for the burn fronts to travel around the charge through different confining paths. Simulations were performed to assess the accuracy of several HE burn methodologies. Experimental data from initiation through HE shock collision will be presented and simulation comparison results will be discussed. [Preview Abstract] |
Wednesday, June 29, 2011 9:45AM - 10:00AM |
L2.00003: The Effects of PBX 9502 Ratchet Growth on Detonation Failure as Determined via the LANL Failure Cone Test Terry Salyer The detonation failure cone test (developed at LANL) functions as a sensitive experimental technique capable of discriminating small detonation performance differences due to material microstructural variations. Detonation performance with respect to failure is visibly amplified in the edge velocity trajectory measured along a conically shaped explosive. The failure cone test has been fielded to examine the possible effects of PBX 9502 ratchet growth (material expansion due to thermal cycling) on detonation failure. Performance comparisons are made between charges of equal density, but with different microstructures due to charge preparation technique. Material porosity complexities affect hot spot distribution and thus the reaction zone characteristics of PBX 9502. The results indicate that ratchet growth does indeed affect detonation performance with respect to failure. [Preview Abstract] |
Wednesday, June 29, 2011 10:00AM - 10:15AM |
L2.00004: DSD-Consistent JWL Equations of State for EDC35 Alexander Hodgson The Detonation Shock Dynamics model (DSD) allows the calculation of curvature-dependent detonation propagation. It is of particular use when applied to insensitive high explosives, such as EDC35, since they have a greater non-ideal behaviour. The DSD model has been used in conjunction with an experimental cylinder test to obtain the JWL Equation of State (EoS) for EDC35. Adjustment of parameters in the JWL equation changes the expansion profile of the simulated wall expansion. The parameters are iterated until the best match can be made between simulation and experiment. Previous DSD models used at AWE have no energy release mechanism to adjust the release of chemical energy to match the detonation conditions. Two JWL calibrations are performed using the DSD model, with and without Hetherington's energy release model (these proceedings). Also in use is a newly-calibrated detonation speed-curvature relation that is much closer, compared to previous calibrations, to Bdzil's equivalent for PBX9502. This paper discusses the possible improvements that this approach makes to the EDC35 JWL EoS. [Preview Abstract] |
Wednesday, June 29, 2011 10:15AM - 10:30AM |
L2.00005: Front curvature and rate stick data on formulations containing DAAF, TATB, RDX and HMX including diameter and temperature effects Elizabeth Francois, Eric V. Sanders, John Morris A test series was conducted on formulations containing TATB and RDX (PBXN-7), TATB and HMX (PBXW-14) and DAAF and HMX where corner turning and detonation propagation data are measured. Corner turning is a function of temperature and can be used to evaluate the completeness of explosive work. In order to show cold temperature performance behavior, this test was developed to compare the front curvature of these materials at a variety of diameters, explosive compositions, and temperature. Shots were fired at ambient temperatures and -55$^{\circ}$C. The test apparatus developed for this lends itself to streak imagining across the pellet face, and time of arrival scope data from magnet wire embedded between the pellets. The test set up, fixturing and data analysis will be discussed. The results of the shots showed interesting diameter effects on the detonation velocity of the formulations and gave an excellent comparison of the relative curvatures. Quantitative data in the form of D$_{n}(\kappa )$ curves are generated from the measured detonation velocity (D$_{o})$ and wave profile. [Preview Abstract] |
Wednesday, June 29, 2011 10:30AM - 10:45AM |
L2.00006: Effect of Shockwave Curvature on Run Distance Observed with a Modified Wedge Test Richard Lee, Robert Dorgan, Gerrit Sutherland, Ashley Benedetta, Christopher Milby The effect of wave curvature on shock initiation in PBXN-110 was investigated using a modified wedge test configuration. Various thicknesses of PBXN-110 donor slabs were used to define the shockwave curvature introduced to wedge samples of the same explosive. The donor slabs were initiated with line-wave generators so that the introduced shock would be the same shape, magnitude and duration across the entire input surface of the wedge. The shock parameters were varied for a given donor thickness via different widths of PMMA spacers placed between the donor and the wedge. A framing camera was used to observe where initiation occurred along the face of the wedge. Initiation always occurred at the center of the shock front instead of the sides like that reported by others using a much smaller test format. Results were compared to CTH calculations to indicate if there were effects associated with highly curved shock fronts that could not be adequately predicted. The run distance predicted in CTH for a 50.8 mm thick donor slab (low curvature) compared favorably with experimental results. However, results from thinner donor slabs (higher curvature) indicate a more sensitive behavior than the simulations predicted. [Preview Abstract] |
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