A reaction progress variable modeling approach for non-ideal multiphase explosives

Abstract

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.

Nanoscopic fuel-rich thermobaric formulations: Chemical composition optimization and sustained secondary combustion shock wave modulation

“…Even though, the peak overpressure (P 1 ) for TBX is lower than (P 2 ) for conventional explosives; it lasts for longer time. Consequently, the total impulse (integrated area under the curve) for TBX is much higher than that for conventional explosives [11]. This is why TBX cause effective damage to structures and fortified persons in caves [12,13].…”

“…Thermochemical calculation was reported to be a promising tool to optimize the chemical formation of TBX [23][24][25]. Numerical simulation enables the prediction of the explosion power of big TBX calibers via experimental data obtained from small scale test [11,26,27]. Therefore, it minimizes the number of required tests which are costly.…”

A multi-phase theory for the detonation of granular explosives containing an arbitrary number of solid components

“…Because the compression contribution cannot be expressed as an explicit algebraic function due to the presence of ∇ · u p in dρ p /dt p , this term is not evolved separately in Eq. (36). Instead, the energy balance equation is first used to evolve phase temperatures through the use of the equation of state.…”

“…The aluminum particles are taken to consist of an inner core of pure metal, initially coated with an oxide layer of thickness δ 0 m . Unlike the detailed metal reaction pathways and phase change processes considered in [36], the thermodynamics and oxidation mechanics of the aluminum component are simplified here, both for modeling tractability and isolating the effects of metal reactions on the system energetics; details of this procedure are provided in [11]. The aluminum oxidation results in metal phase self-heating.…”

“…In particular, Fedorov and Khmel use these constitutive laws in constructing a steady, twophase Eulerian model [14], although their analysis is restricted entirely to the detonation wave structure, and is unable to examine the flow properties in the expansion wave behind the reaction zone; moreover, the steady model has the same limitations as the unsteady models mentioned here in partitioning dissipation energy between phases in a physically plausible manner. Recently, a Lagrangian model with hybrid mixture/multiphase evolution equations was developed by Ruggirello et al [36] to account for more complex oxidation mechanisms and metal phase change. However, the multiphase component is limited to the BN description, and the numerical strategy for the model implementation within an Eulerian framework is cumbersome due to an additional grid remap step which is not present in standard finite-volume schemes.…”