Modeling Compressive Reaction in Shock-Driven Secondary Granular Explosives

Hexanitrostilbene (HNS) is a secondary, granular explosive with a wide usage in commercial and governmental sectors. For example, HNS is used in the aerospace industry as boosters in rockets, in the oil and gas industry in linear shaped charge designs in wellbore perforating guns, and in a number of applications in the US Department of Energy (DOE) and Department of Defense (DoD). In many of these applications, neat granules of HNS are pressed without binder and device performance is achieved with shock initiation of the powdered bed. Previous studies have demonstrated that powdered explosives do not transmit sharp shocks, but produce dispersive compaction waves. These compaction waves can induce combustion in the material, leading to a phenomenon termed Deflagration-to-Detonation Transition (DDT). The Baer-Nunziato (B-N) multiphase model was developed to predict compressive reaction in granular energetic materials due to shock and non-shock inputs using non-equilibrium multiphase mixture theory. The B-N model was fit to historical data of HNS, and this model was used to predict recent impact experiments where samples pressed to approximately 60% of theoretical maximum density (TMD) were shock loaded by high-velocity flyers [1]. Shock wave computations were performed using CTH, an Eulerian, multimaterial, multidimensional, finite-volume shock physics code developed at Sandia National Laboratories [2]. Predicted interface velocities using the B-N model were shown to be in good agreement with the measurements. Furthermore, an uncertainty quantification study was performed and the computational results are presented with best estimates of uncertainty.