Investigation of finite reaction zone effects on the calibration of the condensed-phase high explosive products equation of state

The prediction of high explosive (HE) performance in engineering geometries requires precise knowledge of the HE’s constitutive relations. Specifically, the detonation products equation-of-state (EOS) is key in determining the explosive’s ability to accelerate surrounding materials. Though the products EOS can be generated using theoretical thermochemical equilibrium approaches and knowledge of the molecular constituents, this does not generally achieve the needed predictive accuracy in many engineering design applications. Instead, the products EOS is directly calibrated to cylinder expansion experiments via the use of iterative continuum-level hydrodynamic multi-material simulations. In these experiments, an axisymmetric cylindrical charge confined by a copper liner is detonated and the expanding outer wall trajectory is measured, in order to constrain the detonation products EOS. Due to the large number of required simulations, the hydrodynamic flow in the HE is calculated using efficient, sub-scale Programmed Burn (PB) methodologies which separately set the detonation’s progress and energy delivery. However, the PB methods available to model the flow in the HE have expanded in number and complexity since this methodology was first established. Here, we produce a suite of calibrated products EOS models generated using a variety of HE flow treatments in the detonating explosive, spanning classical (i.e. infinitely thin reaction zone limit) to modern PB methods which incorporate finite reaction zone effects. The predictive capability of each constitutive model variant is then investigated and compared.