Flame acceleration in channels with obstacles in the deflagration-to-detonation transition

摘要

It was demonstrated recently in Bychkov et al., Phys. Rev. Lett. 101 (2008)164501, that the physical mechanism of flame acceleration in channels withobstacles is qualitatively different from the classical Shelkin mechanism. Thenew mechanism is much stronger, and is independent of the Reynolds number. Thepresent study provides details of the theory and numerical modeling of theflame acceleration. It is shown theoretically and computationally that flameacceleration progresses noticeably faster in the axisymmetric cylindricalgeometry as compared to the planar one, and that the acceleration rate reduceswith increasing initial Mach number and thereby the gas compressibility.Furthermore, the velocity of the accelerating flame saturates to a constantvalue that is supersonic with respect to the wall. The saturation state can becorrelated to the Chapman-Jouguet deflagration as well as the fast flamesobserved in experiments. The possibility of transition from deflagration todetonation in the obstructed channels is demonstrated.