Identifier

etd-11112013-154655

Degree

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

Document Type

Dissertation

Abstract

Metal powders are often used as an additive to conventional high explosives to enhance the post-detonation blast wave. Piston-impact simulations are commonly utilized to predict performance metrics such as detonation speed and strength, as well as assessing the impact and shock sensitivity of these materials. The system response is strongly influenced by the initial particle size distribution and material composition. Multiphase continuum models have been routinely applied at the macroscale to characterize the detonation of solid high explosives over engineering length scales. Current models lack a description of the physically permissible constitutive relations for mass transfer due to general chemical reactions between multiple components. The model developed in this study is a major extension of one formulated for an inert mixture to include these reactions, which features a rigorous analysis of the energetic processes that identically satisfy the Second Law of Thermodynamics. Additional features of the model include evolutionary equations which predict phase temperature changes due to individual dissipative heating processes. Macroscale models often include nonconservative source terms that prevent the system of evolutionary equations from being posed in divergence form. A significant challenge in the development of numerical methods to solve these model equations is the proper inclusion of discretizations for the nonconservative sources. In the present work a novel modification of a centered finite-volume scheme is formulated, which is a rigorous extension of a conservative method to include nonconservative sources. This numerical scheme was used to perform a parametric study of metalized explosives containing the high explosive HMX (C4H8N8O8), with both inert and reactive aluminum. Wave speeds, structures, and energetics were shown to exhibit a strong dependence on metal grain size, with reactive aluminum significantly accelerating the detonation speed for the mixture above that of pure HMX for d_m < 500 nm.

Date

2013

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Gonthier, Keith

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