Experimental investigations on flame stabilization behavior in a diverging micro channel with premixed methane–air mixtures

In the present paper, experimental investigations on the characterization of flame stabilization behavior in a 2.0 mm wide diverging channel are carried out with premixed methane–air mixtures. The effect of mixture equivalence ratio (Ф) and flow rate on flame shape, position, stability and emissions are reported in this work. The diverging portion of channel is preheated from the bottom side with a sintered metal burner to provide a positive temperature gradient along the direction of fluid flow which helps in stabilizing a flame in the channel. For a range of velocities and equivalence ratios, different types of stable and partially stable flame propagation modes were observed. Flames obtained for rich mixtures exhibited more stable nature as compared to lean mixtures. The flame stability limits were observed to vary between 0.2 m/s and 1.9 m/s for a range of mixture equivalence ratios.