Extinction behavior of counterflow premixed flames with heterogeneous inlet composition

One-dimensional premixed laminar counterflow flames with heterogeneous inlet composition are investigated numerically for methane/air and Jet A/air mixtures. Different mass flow rates and equivalence ratios into the two opposing nozzles are prescribed such that identical total mass flow rates of air and fuel and total mass flow rates of fuel are maintained across different cases. The effects of heterogeneous inlet compositions on the extinction behavior are then discussed for various sets of inlet equivalence ratio. Budget analysis and chemical explosive mode analysis are employed to understand flame dynamics and to identify the major species contributing to the diffusion. It has been found that heterogeneous inlets can increase the extinction limit due to the back support from the opposing flame. Finally, insights obtained from the one-dimensional counterflow flames are utilized to construct a simple model to mimic the extinction behavior and to enable parametric studies.