Combustion Regimes of Low Stretched Premixed Methane–Hydrogen–Air Mixtures near Flammability Limits

The experimental study of counterflow premixed low-stretched flames stabilized in a flat channel is described in the paper. A premixed methane-air mixture was investigated. The effect of the channel gap on the flammability limits was evaluated. It was found that increasing the channel gap expands the flammable region to a lean mixture area. The effect of the hydrogen addition on the flammability limits was also studied as part of the paper. This leads to lower Lewis numbers and various unstable combustion modes such as running waves, moving cells and sporadic flames. Similar modes have been observed previously in microgravity experiments. The obtained combustion modes were classified, and the area of premixed methane-hydrogen-air flames existence was determined. Additionally, the regime diagram for the mixture with hydrogen content of 50% by volume in the fuel was plotted as a results of this study.