Characteristics of microscale combustion in a narrow heated channel

The characteristics of microscale combustion were investigated by using a microchannel heated by an external source. The inner diameter of the channel was 2 mm, which was slightly smaller than the quenching distance of the stoichiometric methane–air mixture under normal conditions. The effects of the equivalence ratio and the averaged flow velocity on the characteristics of combustion in the microchannel were examined. At a channel-wall temperature of $\approx$1000$^\circ$C, flames could be stabilized at equivalence ratios of 0.05–1.9 and mixture velocities up to 150 cm/sec in a U-shaped quartz-glass channel. At moderate equivalence ratios and lower velocity conditions within the flammability region, oscillatory combustion was observed. A simple analytical model predicting flame oscillations on the basis of the linear analysis of steady solutions is proposed.