Thermal loading of explosives--finite difference method with time step reduction.
The method of simulation of heat transfer during thermal loading of energetic materials is introduced. The combination of the simple finite difference method with a time step reduction enables the quick and precise calculation of ignition times. The results are in accordance with published model data. The method was also used to simulate heat transfer during the slow cookoff test and the result agrees very well with experimental data.
A Model for High Explosive Cookoff
We have continued to improve our ability to model the response of energetic materials to thermal stimuli and the processes involved in the energetic response. Several new algorithms have been developed to increase the accuracy and fidelity of the modeling process. These include a level set driven multi-material deflagration model, a multi-temperature mixed material treatment, self-consistent thermal-hydro coupling, full implicit quasi-static hydrodynamics, ale slide surfaces and ale slide deletion. These capabilities have allowed us to improve our ability to model the cookoff process from the initial application of heat to the final metal expansion.
The equation of state of supercritical HF, HCl, and reactive supercritical mixtures containing the elements H, C, F, and Cl
We develop a model of chemical equilibrium mixtures containing the elements H, C, F, and Cl. The model is based on a recently developed equation of state for the exponential-6 fluid, combined with a simple equation of state for condensed carbon. We show that the shock response of a wide variety of molecular and polymeric fluorocarbons and chlorocarbons can be modeled as a chemical equilibrium mixture of a small number of dissociation product molecules. In particular, we predict that shocked polyvinylidine fluoride (PVF2) decomposes into a fluid phase composed mostly of HF, and a phase containing condensed carbon. HF is known to strongly associate in the supercritical fluid phase. We predict that such an association also occurs under shock conditions.