Spherical Combustion Clouds in Explosions (Rev 5a)

This study investigates combustion clouds embedded in unconfined spherical explosions. Two charge configurations are considered: a 0.5-g spherical PETN booster surrounded by a spherical shell of either 1-g of TNT solid or of 1-g of Aluminum (Al) powder; these provide the fuel for the combustion process. Detonation of booster disperses the fuel, whose expansion drives a blast wave into the surrounding atmosphere. The fuel-air interface is unstable and rapidly evolves into a turbulent mixing layer. The hot detonation products and the shock-heated air serve as ultra-strong ignition sources of the fuel-air mixture, which evolves into a spherical combustion cloud [1,2]. The evolution of the blast wave and ensuing combustion cloud dynamics are studied via numerical simulations with our two-phase Adaptive Mesh Refinement (AMR) combustion code [3,4]. 2 Model Conservation Laws The Model is based on the Eulerian multi-phase conservation laws for a dilute heterogeneous continuum, as formulated by Nigmatulin [6]. We model the evolution of the gas phase combustion fields in the limit of large Reynolds and Peclet numbers, where effects of molecular diffusion and heat conduction are negligible. The flow field is governed by the gas-dynamic conservation laws: Mass: