Computational study on the stability of lean CH4-air and H2-CH4-air laminar premixed flames

Recently, Shoshin et al. [1] reported measurements on blow-off limits for methane-air and hydrogen-methaneair flames stabilized on metallic rods finding a so-called "anomalous" blow-off behaviour of hydrogen-methaneair flames with certain hydrogen content. It is well known that lean methane-air and hydrogen-methane-air flames have characteristics that differ substantially owing to preferential diffusion effects. In this study, two-dimensional simulations of steady, rod-stabilized, inverted, lean, methaneair and hydrogen-methane-air premixed laminar flames are performed to further investigate the stability and blowoff characteristics of such flames. The simulations are carried out with complex chemistry and non-unity Lewis transport. For the hydrogen-methane-air flames, mixtures with a 40% (molar based) hydrogen content in the fuel are considered. Six cases for different values of equivalence ratio, , and mean inlet velocity, V , of the premixed mixture are studied. The conditions for all the cases are summarized in Table 1. In what follows, the governing equations are provided, the burner and computational setup are described and the numerical results are discussed.