Numerical investigations of nonideal explosions

Abstract

This study focusses on nonideal free-field blast waves arising from the finite rate of energy addition in a distributed nonspherical source region. The behavior of the blast wave is determined in a compressible medium surrounding a centrally ignited flammable mixture during and after the propagation of a heat addition wave which models the detonative or deflagrative combustion process. Numerical integration of the nonsteady, two-dimensional Euler equations is performed by incorporating a heat addition “two-gamma” working fluid model to represent the flame or detonation wave. This study also investigated the behavior of a blast wave generated by the burst of a high-pressure ellipsoid. The effect of the heat addition waves on the near and far field blast waves was studied by determining the relevant blast parameters, peak overpressure, and positive phase impulse, as well as the detailed evolution of the gas dynamic variables with time and distance. The blast parameters which correspond to low velocity flames compare favorably with those obtained using linear acoustic monopole theory. The results indicate that pressure relief associated with the presence of a compressible inert medium surrounding the combustion products after the flame propagates to the interface of nonspherical clouds sevrely restricts the intensity of the explosion and thereby reduces the damages that can be produced by the blast wave.