RADIATION EXTINCTION LIMIT OF COUNTERFLOW PREMIXED LEAN METHANE-AIR FLAMES

The application of the laminar flamelet concept to turbulent flame mod eling requires a detailed understanding of stretched laminar flames. I n this study, we used numerical methods, including are-length continua tion, to simulate the extinction characteristics of counterflow premix ed fuel-lean, methane-air flames. Attention was primarily paid to the effect of radiative heat loss on the extinction characteristics of the se flames. The results show that at medium to low values of the stretc h rate, the radiative heat loss has a particularly strong impact on th e counterflow premixed fuel-lean, methane-air flames. It was also foun d that, in addition to the stretch extinction limit at a high stretch rate, there exits a radiation extinction limit at a low stretch rate. Furthermore, the relationship between these two extinction limits and the equivalence ratio is obtained. (C) 1997 by The Combustion Institut e.