Laminar non-premixed flame calculations of methane with highly-preheated air

Flameless Oxidation (FLOX) is a combustion regime incorporating recirculation of hot combustion products to the oxidant stream to oxidize the fuel without having a flame. The laminar nonpremixed flame was studied computationally using the OPPDIF code using methane as fuel while the air was diluted with combustion products to alter the oxygen levels in the oxidant stream. The chemical kinetics mechanism consisted of 51 species and 200 reactions including nitrogen oxidation. The GRI-2 mechanisms did not sustain methane flames below 1400 K. The methane nonpremixed laminar flame computations underpreheated oxidizer stream conditions and at low strain rate displayed a number of characteristics; an increase in the oxidizer stream temperature broadened the reaction zone and displayed a distributed reaction regime; the OH radical at the FLOX conditions did not seem to be important while CH2O species increased significantly; and at above 1200 K and low oxygen levels, the combustion regime was similar to that of the FLOX regime. Original is an abstract.