DETONATION INITIATION IN A COMBUSTIBLE GAS MIXTURE AT INTERACTION OF A SHOCK WITH INERT GAS BUBBLE

Abstract

Using the Euler equations for a perfect gas with an inhomogeneous distribution of molar mass, the interaction of a shock wave in a combustible gas with an elliptic bubble of an inert gas of increased density is simulated in plane two-dimensional formulation. Various values of the Mach number M of the incident wave and the ratio of bubble axles are considered. A finite-volume S. K. Godunov-type method of the second order of approximation with HLLC (Harten – Lax – van Leer-contact) Riemann solver is used for numerical simulation. The combustion reaction of the gas mixture is modeled using the two-stage Korobeynikov–Levin kinetics. Various regimes of mixture ignition are described. At sufficiently large Mach numbers of the incident wave, the combustion of the mixture is initiated directly due to heating in the shock wave. For weaker shocks, ignition may occur when the incident shock wave is reflected from the gas interface and for even weaker shocks, upon the shock focusing near the leeward pole of the bubble. It is shown that the shape of the bubble also plays an important role, in some cases providing the initiation of combustion by a weaker wave, or, conversely, the absence of ignition.