An Eulerian–Lagrangian approach for simulating explosions of energetic devices

Abstract

An approach for the simulation of explosions of "energetic devices" is described. In this context, an energetic device is a metal container filled with a high explosive (HE). Examples include bombs, mines, rocket motors or containers used in storage and transport of HE material. Explosions may occur due to detonation or deflagration of the HE material, with initiation resulting from either mechanical or thermal insult. This approach is applicable to a wide range of fluid-structure interaction scenarios, the application to energetic devices is chosen because it demonstrates the full capability of this methodology.Simulations of this type are characterized by a number of interesting and challenging behaviors. These include the transformation of the solid HE into highly pressurized gaseous products that initially occupy regions which formerly contained only solid material. This rapid pressurization of the container leads to large deformations at high strain rates and its eventual case rupture. Once the container breaks apart, the highly pressurized product gas that escapes the failing container generates shock waves that propagate through the initially quiescent surrounding fluid.The approach, which uses a finite-volume, multi-material compressible CFD formulation, within which solid materials are represented using a particle method known as the Material Point Method, is described, including certain of the sub-grid models required to close the governing equations. Results are first presented for "rate stick" and "cylinder test" scenarios, each of which involves detonating unconfined and confined HE material, respectively. Experimental data are available for these configurations and as such they serve as validation tests. Finally, results from an unvalidated "fast cook-off" simulation in which the HE is initiated by thermal input, which leads to a deflagration type of reaction, are shown.

A reactive flow model for heavily aluminized cyclotrimethylene-trinitramine

“…P is the pressure, t is the time, and q 0 and q are the initial and current densities, respectively. The MieGruneisen equation of state (EOS) 5 in Eq. (2) is for the unreacted solid HE, and the isentropic JWL EOS 6 in Eq.…”

The influence of an applied heat flux on the violence of reaction of an explosive device

“…The MPM-ICE algorithm [11] is used to solve the governing equations for our reacting fluid-structure-interaction (FSI) problem and is implemented in Uintah as a "component." In addition to the MPM-ICE algorithm, Uintah integrates numerous sub-components including equations of state, constitutive models and solid→gas reaction models.…”

Using hybrid parallelism to improve memory use in the Uintah framework

“…This is a multi-physics, large deformation, fluid-structure problem consisting of a small cylindrical steel container filled with a plastic bonded explosive (PBX9501) subjected to convective and radiative heat fluxes from a fire [12].…”

“…Uintah currently contains three main simulation algorithms, or components, that are capable of using Adaptive Mesh Refinement (AMR): the ICE compressible multi-material CFD formulation, the particle-based Material Point Method (MPM) for structural mechanics, the combined fluid-structure interaction algorithm MP-MICE [12].…”