Initiation of Detonation when a Shock Wave Hits a Flammable Gas Cylinder near a Solid Wall
O. G. Sutyrin1, P. Yu. Georgievskiy1, V. A. Levin1,2
1Institute of Mechanics Lomonosov Moscow State University, Moscow, Russia
2Kutateladze Institute of Thermal Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: shock wave, gas bubble, wall, focusing, cumulation, combustion, ignition, detonation
Abstract
Using the Euler equations in a two-dimensional plane, we numerically study the incidence of a shock wave on a near-wall gas bubble (a transverse cylinder) filled with a hydrogen-oxygen mixture doped with xenon. Gas combustion is modeled using detailed kinetics, taking into account 19 reversible reactions. A high-order finite-difference method of the WENO class is applied. The processes of shock wave refraction and reflection, as well as the focusing of secondary shock waves, are described. Various modes of detonation initiation in the bubble are discovered: direct detonation, refraction and reflection of the wave from the wall, and focusing of shock waves on a plane of symmetry near the wall. Based on a series of calculations, the dependence of ignition modes and threshold Mach numbers of the incident wave on the bubble shape is determined. It has been shown that the combination of wave focusing on the bubble and reflection from the wall leads to a significant reduction in threshold Mach numbers, both compared to a flat layer of combustible gas in front of the wall and compared to a free bubble without a wall.
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