On detonation diffraction in condensed-phase explosives

We consider cases that are designed to model condensed-phase explosives to study the diffraction of a detonation into an unconfined region of explosive. We use direct numerical simulations and study dynamic transients in self-similar coordinates. We consider an ideal equation of state and state-insensitive and state-sensitive reaction rate laws that mimic condensed explosives. We find through an analysis of shock arrival times that the cylindrical detonation is useful in describing the dynamics of the expansion region in a two-dimensional detonation diffraction event.; The wide-ranging equation of state is a non-ideal equation of state based on empirical fitting forms argued from thermodynamic considerations that yield the proper physical features of detonation. The complete equation-of-state forms and a reaction rate are calibrated for the condensed-phase explosive PBX-9502. Experimental overdriven Hugoniot data are used to calibrate the products equation of state off the principal isentrope passing through the Chapman-Jouguet state. Shock Hugoniot data are used to calibrate the reactants equation of state. The normal-shock-velocity-shock-curvature data from rate-stick measurements and shock initiation data from wedge tests are used to calibrate the reaction rate.; We present an integrated algorithm for multi-material simulations of energetic and inert materials modeled by non-ideal equations of state. We employ recent shock-capturing numerical algorithms for each material inside the domain of definition, use an overlap domain method across the interface, and present an accurate moving-interface-tracking algorithm. We present simulations of various engineering devices containing energetic materials in practical engineering situations. The equation of state and reaction rate for PBX-9502 are also validated against experiment.; A recently proposed higher order theory including shock acceleration effects for detonation shock dynamics (DSD) is evaluated for PBX-9502. Comparisons of detonation diffraction in PBX-9502 are made between experiment, multi-material simulations using the calibrated equation of state and reaction rate, and DSD simulations using the computed higher order relation for PBX-9502. The equation of state and reaction rate developed predicts the corner-turning distance for PBX-9502. The higher order DSD relation predicts a small dead zone at the corner, an improvement over the quasi-steady theory.