Flame acceleration in deflagration-to-detonation transition



Title：	Flame acceleration in deflagration-to-detonation transition
Speaker：	Vitaliy Bychkov (瑞典Umea大學物理系)
Time：	3月5日（周二）下午2:00-4:00，物理系三樓報告廳.
Abstract:	A premixed combustion front propagates either as a slow subsonic flame (deflagration) or fast supersonic detonation; their velocities differ by 3-4 orders of magnitude. However, at certain conditions a slow flame may spontaneously accelerate and trigger detonation. A deflagration-to-detonation transition (DDT) is the key point, for example, for explaining Thermonuclear Supernovae (Type Ia) and in the design of pulse-detonation engines of the new-generation aircrafts; it stands also behind many disasters like explosions in rockets, nuclear plants and mines. Spontaneous flame acceleration is the reason and the most important stage of the DDT. In this talk I will present our results on the flame acceleration process. The presentation includes both development of the classical Shelkin mechanism of flame acceleration in tubes with smooth walls, and the new ultra-fast mechanism of flame acceleration in obstructed channels, explained by our group. Moderation of the flame acceleration process at the developed stages and explosion triggering will be also discussed.