  It was demonstrated recently in Bychkov et al., Phys. Rev. Lett. 101 (2008)
164501, that the physical mechanism of flame acceleration in channels with
obstacles is qualitatively different from the classical Shelkin mechanism. The
new mechanism is much stronger, and is independent of the Reynolds number. The
present study provides details of the theory and numerical modeling of the
flame acceleration. It is shown theoretically and computationally that flame
acceleration progresses noticeably faster in the axisymmetric cylindrical
geometry as compared to the planar one, and that the acceleration rate reduces
with increasing initial Mach number and thereby the gas compressibility.
Furthermore, the velocity of the accelerating flame saturates to a constant
value that is supersonic with respect to the wall. The saturation state can be
correlated to the Chapman-Jouguet deflagration as well as the fast flames
observed in experiments. The possibility of transition from deflagration to
detonation in the obstructed channels is demonstrated.
