Analysis of Highly CO₂-Diluted Oxy-propane Flames Stabilized over a Multihole Burner of a Model Gas Turbine Combustor

Premixed oxy-propane flames are investigated numerically in a multihole model gas turbine combustor at various inlet mixture compositions over a range of equivalence ratios (Ø: 0.241-0.500), oxygen fractions (OF: 32.4-60.0%), and adiabatic flame temperatures (T_ad: 1600-1900 K) at a constant bulk throat velocity of 5.2 m/s. The flames in multihole combustors are highly influenced by their corresponding adiabatic flame temperatures. Similar flame shapes are observed at constant T_ad, where cases with (Ø = 0.241, OF = 60%) and (Ø = 0.50, OF = 32.4%) both represent lifted flames at T_ad= 1600 K, anchored flames in (Ø = 0.276, OF = 60%) and (Ø = 0.50, OF = 36.6%) at T_ad= 1750 K, and anchored stronger flames in cases (Ø = 0.313, OF = 60%), (Ø = 0.392, OF = 50%), and (Ø = 0.50, OF = 40.8%) at T_ad= 1900 K. Flames in a multihole combustor are characterized by the presence of an outer recirculation zone (ORZ) only. In comparison with a swirl-stabilized combustor in identical inlet conditions, flames in a multihole combustor demonstrate a lower Damköhler number (Da), higher flame thickness, elevated pattern factor, and increased CO emission. Due to the reduced vorticity level because of the absence of swirl motion, the multihole flames have higher axial temperature than the swirl-stabilized ones.