Flame Stabilization Behavior of a Heated Reacting Premixed Jet in a Hot Vitiated Crossflow

摘要

The objective of this experiment was to determine the effect of flame speed on flame stabilization characteristics of a reacting premixed ethylene-air jet injected normally into the hot vitiated crossflow of lean combustion products. This study was motivated by our previous work which indicates that flame stabilization is controlled by both auto-ignition and flame propagation. Here the auto-ignition timescale as defined by the most-reactive mixture fraction is held constant to isolate the changes in flame stabilization location due to the effects of flame propagation. A parametric study was performed over jet-to-crossflow momentum ratios from J=5 to J=25 by changing the jet momentum via jet exit velocity. Laminar flame speed for the jet mixture was varied by a factor of four by varying the jet mixture temperature from 300K to 600K, thus providing a means to investigate the sensitivity of flame stabilization to this parameter. Chemiluminescence imaging was used to determine the flame stabilization location for each condition. Additional tests varying the jet equivalence ratio were performed to determine sensitivity to mixture strength and to verify trends. An analysis of experimental data is offered based on the chemical and flow timescales (or Damkohler number) to better understand the effects of auto-ignition and flame propagation on flame stabilization behavior.