Response of stoichiometric and rich premixed methane-air flames to unsteady strain rate and curvature

The interaction of a premixed methane-air dame with a two-dimensional count errotating vortex pair is studied under stoichiometric and rich conditions using a detailed C1C2 chemical mechanism. The flame structure and transient response are examined, both at curved cusps and on the vortex-pair centrel ine. Differences between the two flames are observed in the unsteady behavi our of species mole fractions and production rates. In contrast with earlie r one-dimensional opposed-jet flame data, the present results show that the rich flame exhibits a faster response to unsteady strain-rate disturbances than does the stoichiometric flame. Analysis of the results suggest this m ay be due to the increased dependence of the dame on H, and the decreased r ole of OH, under rich conditions. Results are also presented from an experi mental V-flame vortex-pair interaction study. Measured peak CH and OH data are also found to exhibit a faster flame response under rich conditions.