Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session J5: CM-4: Continuum Modeling of Reactive Materials and Dynamic Response |
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Chair: James Quirk, Los Alamos National Laboratory Room: Cheekwood GH |
Tuesday, June 30, 2009 11:00AM - 11:15AM |
J5.00001: Modeling Solid State Detonation and Detonation with Designed Microstructure Sunhee Yoo, D. Scott Stewart, David E. Lambert Solid state detonation refers to nonclassical supersonic reactive wave phenomena in energetic materials that are not typically considered explosives. Reactive energetic materials include both metal/metal oxide and metal oxide/polymer systems with thermitic reaction. Like conventional solid explosives, the materials are manufactured composites with a well-defined microstructure. Ingredients include nano-engineered energetic materials with novel surface and reaction properties. The manufactured materials are still described by a continuum limit informed by the microstructural properties. We consider limit model formulations that include acoustic dispersion phenomena, intermaterial heat transfer and void effects and macroscopic ignition and extinction of steady traveling reactive waves, in a modeling framework that can aid the design of new materials. [Preview Abstract] |
Tuesday, June 30, 2009 11:15AM - 11:30AM |
J5.00002: Integrated Experiment and Modeling of Insensitive High Explosives D. Scott Stewart, David E. Lambert, Sunhee Yoo, M. Lieber, Steven Holman New design paradigms for insensitive high explosives are being sought for use in munitions applications that require enhanced, safety, reliability and performance. We describe recent work of our group that uses an integrated approach to develop predictive models, guided by experiments. Insensitive explosive can have relatively longer detonation reaction zones and slower reaction rates than their sensitive counterparts. We employ reactive flow models that are constrained by detonation shock dynamics to pose candidate predictive models. We discuss variation of the pressure dependent reaction rate exponent and reaction order, on the length of the supporting reaction zone, the detonation velocity curvature relation, computed critical energy required for initiation, the relation between the diameter effect curve and the corresponding normal detonation velocity curvature relation. We discuss representative characterization experiments carried out at Eglin, AFB and the constraints imposed on models by a standardized experimental characterization sequence. [Preview Abstract] |
Tuesday, June 30, 2009 11:30AM - 11:45AM |
J5.00003: Impact of Volume Fraction Evolution on the Mathematical Model for Multiphase Flow Thomas McGrath A major challenge in multiphase flow modeling is describing the evolution of volume of each constituent in the flow. Volume, or volume fraction, arises as an independent variable in multiphase models not rigidly applying pressure equilibrium, necessitating a separate evolutionary equation for closure. While many existing models adopt the dynamic compaction equation proposed by Baer {\&} Nunziato, this equation is non-unique and may not be physically accurate. In this work, an extended version of the dynamic compaction equation is investigated in the context of a two-phase flow consisting one continuous and one dispersed (particulate) phase. The extended version includes an additional term based on the divergence of the dispersed phase; this allows the behavior of the dispersed phase to range from incompressible to fully-compressible. The governing equations are presented, and a characteristic analysis is performed. Results indicate that the form of the volume fraction equation has a significant impact on the mathematical characteristics of the governing equations. [Preview Abstract] |
Tuesday, June 30, 2009 11:45AM - 12:00PM |
J5.00004: ABSTRACT WITHDRAWN |
Tuesday, June 30, 2009 12:00PM - 12:15PM |
J5.00005: ABSTRACT WITHDRAWN |
Tuesday, June 30, 2009 12:15PM - 12:30PM |
J5.00006: Detonation Shock Dynamics for Porous Explosives and Energetic Materials Juan Saenz, D. Scott Stewart An explosive powder subjected to mechanical or thermal loading undergoes microstructural changes that cause the density to increase and the material to be compacted. The energy that drives compaction is absorbed by the material as the microstructure changes and the specific internal energy of the solid-void mixture increases due to the increase in density as voids become occupied by solids. These changes affect the reactive properties of the material and the mechanics and dynamics of detonation waves in explosive powders. The effects of explosive powder compaction on detonation wave dynamics have not been well characterized. Here we use the theory of Detonation Shock Dynamics (DSD) to analyze the effects of compaction on the dynamics and geometry of detonation waves in explosive powders. We apply DSD theory using a simplified equation of state (EOS) that has been shown to represent the effects of compaction that lead to deflagration to detonation transition in explosive powders. We will show results from the numerical solution of the DSD theory equations as well as from asymptotic DSD theory. [Preview Abstract] |
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