Gas combustion in narrow single channels

Combustion of propane-air mixtures flowing in quartz tubes with internal diameter greater but comparable to the critical diameter was studied experimentally. It was shown that in opposed flame propagation, the flame velocity decreased linearly to almost zero with increasing flow velocity. In the region of zero velocity, there was a transition from the regime of high velocities to a stationary regime with propagation velocities typical of the low-velocity regime (LVR) of filtration gas combustion (about 10$^{-4}$ m/sec). This regime was studied and classified as the LVR-2 in view of its special properties. It was shown that a further increase in the flow velocity led to flame stabilization in the LVR-2. In various ranges of flow velocities, various types of instability of the flame front were observed.