This study concerns the development of a mixture fraction based reaction progress variable formulation for aluminized explosives. Highlights of the formulation include a fully compressible treatment of both the gas and solid phases (both aluminum and alumina), heterogenous and homogenous reactions, and effects of group combustion. Isolated particle simulations are validated against experimental data and DNS and show good agreement of burn times over a range of pressure and oxygen environments. The new models are implemented in the CTH shock physics code using a fractional step approach to allow for efficient computation of particle dynamics. Comparisons are made to experimental pressure data for a thermobaric explosive in the Sandia Explosive Components Facility (ECF). Parametric studies are conducted to determine pressure response and impulse to charge equivalence ratio and particle size. Overall good agreement is observed between simulation predictions of pressure time history and impulse.

Two-phase shock-driven reacting flow simulations are conducted to determine the postdetonation shock-focusing ignition and burning of aluminum particle mixtures. A model for aluminum particles that accounts for material compressibility from shock heating and expansion is presented. The Lagrangian description of the particles is incorporated into an Eulerian description of the gas phase resulting in a fully compressible, twoway coupled simulation. Simulations are conducted of an isolated explosive located near a corner to promote ignition of the particles from shock focusing. Parametric studies are conducted to determine the effects of equivalence ratio, particle size, and charge placement, on the post-detonation pressure and impulse. Results highlight the importance of the timing and position of the shock focusing event relative to the local mixture equivalence ratio that results in an optimal equivalence ratio which maximizes impulse for the geometry considered.

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