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 Q2: Energetic Materials VI |
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Chair: David Frost, McGill University Room: Grand Ballroom IV-V |
Wednesday, June 29, 2011 4:00PM - 4:15PM |
Q2.00001: Close-in Blast Waves from Spherical Charges* William Howard, Allen Kuhl We study the close-in blast waves created by the detonation of spherical high explosives (HE) charges, via numerical simulations with our Arbitrary-Lagrange-Eulerian (ALE3D) code. We used a finely-resolved, fixed Eulerian 2-D mesh (200 $\mu $m per cell) to capture the detonation of the charge, the blast wave propagation in air, and the reflection of the blast wave from an ideal surface. The thermodynamic properties of the detonation products and air were specified by the Cheetah code. A programmed-burn model was used to detonate the charge at a rate based on measured detonation velocities. The results were analyzed to evaluate the: ($i)$ free air pressure-range curves: $\Delta p_s (R)$, (\textit{ii}) free air impulse curves, (\textit{iii}) reflected pressure-range curves, and (iv) reflected impulse-range curves. A variety of explosives were studied. Conclusions are: ($i)$ close-in ($R<10\;cm/g^{1/3})$, each explosive had its own (unique) blast wave (e.g., $\Delta p_s (R,\;HE)\sim a/R^n$, where $n$ is different for each explosive); (\textit{ii}) these close-in blast waves do not scale with the ``Heat of Detonation'' of the explosive (because close-in, there is not enough time to fully couple the chemical energy to the air via piston work); (\textit{iii}) instead they are related to the detonation conditions inside the charge. Scaling laws will be proposed for such close-in blast waves. *This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Wednesday, June 29, 2011 4:15PM - 4:30PM |
Q2.00002: Extension of JAGUAR Procedures for New Gaseous and Condensed Species Leonard Stiel, Ernest Baker, Daniel Murphy JAGUAR is a highly efficient and accurate thermochemical equilibrium program for the detonation properties of explosives. In previous studies equation of state EXP-6 parameters for H-CN-O gaseous explosives product species have been optimized with available individual species Hugoniot data. The Jaguar library also includes solid and liquid properties for carbon and aluminum, silicon, and boron compounds. In this study the Jaguar property library has been expanded to include additional gaseous, liquid, and solid detonation products. New EXP-6 parameters for gaseous fluorine and chlorine compounds have been established through theoretical procedures, and by analyses of Hugoniot data for the actual species or for reactants which decompose into these compounds. Properties for additional condensed species have also been analyzed and added to the library. Extensive tests have beeb performed to determine the accuracy of calculated detonation properties in comparison to experimental data. [Preview Abstract] |
Wednesday, June 29, 2011 4:30PM - 4:45PM |
Q2.00003: Fast Reactions of Aluminum and Explosive Decomposition Products in a Post-Detonation Environment Bryce Tappan, Virginia Manner, Joseph Lloyd, Steven Pemberton In order to determine the reaction behavior of Al in HMX/cast-cured binder formulations shortly after the passage of the detonation, a series of cylinder tests was performed on formulations with varying amounts of 2 $\mu$m spherical Al as well as LiF (an inert surrogate for Al). In these studies, both detonation velocity and cylinder expansion velocity are measured in order to determine exactly how and when Al contributes to the explosive event, particularly in the presence of oxidizing/energetic binders. The U.S. Army ARDEC at Picatinny has recently coined the term ``combined effects explosives'' for these materials as they demonstrate both high metal pushing capability and high blast ability. This study is aimed at developing a fundamental understanding of the reaction of Al with explosives decomposition products, where both the detonation and post-detonation environment are analyzed. Reaction rates of Al metal are determined via comparison of predicted performance based on thermoequilibrium calculations. The JWL equation of state, detonation velocities, wall velocities, and parameters at the C-J plane are some of the parameters that will be discussed. [Preview Abstract] |
Wednesday, June 29, 2011 4:45PM - 5:00PM |
Q2.00004: Air Blast Characteristics for Laminate Al and Al-Ni Composites Fan Zhang Air blast characteristics of laminate Al and Al-Ni composites were investigated in a 23~m$^{3}$ closed chamber. 50 to 100 $\mu $m thick Al-Ni or Al foils were rolled to form a cylindrical shell, which was then compacted to a density larger than 99{\%} TMD through an explosive formation technique. Charges were prepared using 2~kg C4 explosive packed in the laminate metal shell to a metal-explosive mass ratio of 1.75. Pressure and temperature were measured through transducers on the chamber wall and pyrometry sensors facing the charge center. The pressure history showed a double-shock front structure with an accelerating precursor shock of high amplitude followed by the primary blast, suggesting considerable early-time reaction of small laminate fragments. Significant enhanced explosion pressure (QSP) was observed as compared with baseline charges in solid shell. Recovered residue showed fragments in flakes with a considerable fraction in the molten. The pressure and temperature results are further analyzed to distinguish the reaction properties between the Al-Ni (gasless reaction for them alone) and Al laminates as well as their effect on air blast. The results are also compared with previous investigations using various shell materials and compositing techniques. [Preview Abstract] |
Wednesday, June 29, 2011 5:00PM - 5:15PM |
Q2.00005: Laser Dispersion and Ignition of Functionalized Aluminum Particles Jillian Horn, James Lightstone, Joel Carney, Jason Jouet Aluminum nanoparticles prepared in solution by decomposition of an organometallic precursor and functionalized with long-chain perfluorinated carboxylic acids have demonstrated increased performance over H5 Al (8$\mu $m) in small scale shock reactivity tests$^{ }$presumably because the oxide coating has been eliminated. Solution phase preparation for this material, however, is unsuitable for large scale production. This talk will highlight a method for large scale production of air-stable passivated aluminum nanoparticles. Aluminum nanocomposite materials with size ranges less than 500 nm have been prepared with various surface passivation/functionalization schemes that eliminate aluminum oxide and reduce the fuel-oxidizer distance to the molecular level. These materials have been characterized to understand the changes in particle size and morphology that occur with different preparation schemes. TGA, DSC, XRD, and IR spectroscopy results will be presented. Additionally, the combustion characteristics of these air stable fluorinated aluminum nanoparticles are studied and compared to untreated aluminum particles using a laser-dispersion and laser-ignition method developed at the Naval Surface Warfare Center, Indian Head Division. [Preview Abstract] |
Wednesday, June 29, 2011 5:15PM - 5:30PM |
Q2.00006: Development of Metal Cluster-Based Energetic Materials James Lightstone, Joseph Hooper, Chad Stoltz, Becca Wilson, Dennis Mayo, Bryan Eichhorn, Kit Bowen The energy available from the combustion of Al is 2 to 3 times that of conventional high explosives and as a result is often loaded into explosive and propellant formulations in micron and nano-particle form. However, even at the nano-scale the release of energy is slowed by the reaction kinetics of particle oxidation. In order to realize faster reaction rates, on the order of current CHNO explosives, the size of the particles of interest need to be reduced significantly into the molecular size-range (10's of atoms). Current research efforts at NSWC-IHD are utilizing gas-phase molecular beam studies, theoretical calculations, and condensed-phase production methods to identify novel metal cluster systems in which passivated metal clusters make up the subunit of a molecular metal-based energetic material. To date, small amounts of a metal-based compound with a subunit containing four Al atoms and four Cp* ligands has been produced and is currently being characterized using DSC and TGA. Additional Al based systems passivated with a variety of organic ligands are being systematically examined. Analytical and theoretical results obtained for Al$_{4}$Cp*$_{4}$ and the additional cluster systems under investigation along with their potential energetic applications will be presented. [Preview Abstract] |
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