Cross-sections for quenching of CH A²Δ, v′ = 0 by N₂ and H₂O from 1740 to 2160 K

Measurements of time-resolved CH fluorescence were reported for 77 methane-based counter-flow diffusion flames at 1 atm. Seven oxidizer mixtures, with variations in O₂/N₂/Ar mole fractions, were used with each of 11 CH₄/N₂/Ar fuel mixtures to vary the resulting nitrogen mole fraction without altering the flame temperature. N₂ quenching of CH A ²Δ, ν′ = 0 at flame temperatures was less efficient by a factor of three than the correlation of Tamura et al., which relied on extrapolation from a single measurement at 1300 K. The collision environment for the 77 diffusion flames was predicted using OPPDIF with GRI-3 kinetics and the resulting data were used to suggest improvements to the H₂O thermally-averaged cross-section. The present data were consistent with a constant H₂O cross-section vs. temperature as opposed to a constant quenching rate coefficient, as suggested in prior work. Original is an abstract.