Detonation Initiation upon Interaction of a Shock Wave with a Combustible Gas Bubble of Various Densities

Interaction of a shock wave in a gas with a combustible high-density gas bubble is numerically simulated based on the Euler equations. Three qualitatively different modes of detonation initiation are described: direct initiation of detonation at the head of the bubble at sufficiently high Mach numbers of the incident wave and detonation initiation at the rear of the bubble due to wave refraction and the focusing of secondary shock waves at lower Mach numbers. It is shown that the detonation initiation mode largely depends on both the shock wave intensity and the density of the mixture in the bubble. Based on a series of computations, a diagram of initiation modes is constructed and it is shown that the effect of shock wave focusing ensures successful detonation initiation with a much lower intensity of the incident wave compared to direct initiation.