Ultra-rich fuel dynamics of a holder-stabilized premixed flame in a preheated mesoscale combustor

The present work experimentally studies the laminar premixed flame dynamics at fuel ultra-rich condition under the synergistic effect of heat and flow recirculation, which take place in many practical combustors, such as aero engines. The normal, anomalous, and low speed blow-off phenomena are observed. Furthermore, the anomalous standoff distance between the flame root and the holder is found for the first time at fuel rich condition. Interestingly, with an increase in the equivalence ratio, the oscillating flame appears before blow-off at Reynolds number Re >= 60. The stability limit first increases and then decreases with a decrease in Re, which is also reported for the first time. If the equivalence ratio is increased further, the oscillating flame at Re >= 60 blows off with a small timescale, while the stable flame at Re < 60 gradually acquires a flat behavior, and then shifts downstream at a very slow speed. (C) 2020 Elsevier Ltd. All rights reserved.