Structural study of non-premixed tubular hydrocarbon flames

Tubular non-premixed flames are formed by a uniquely designed opposed tubular burner. Structural measurements of hydrocarbon flames are conducted using the laser-induced Raman scattering technique. Temperature and major species concentrations are recorded for flames produced by 30% CH₄/N₂ and 15% C₃H₈/N₂ burning against air. Numerical simulations of these flames with detailed chemistry show good agreement between the measured and simulated results. By comparing the numerical results of the tubular curved flames to those of the opposed-jet planar flames, it is shown that flame curvature towards the fuel stream strongly effects the temperature (±80 K) of flames with low fuel Lewis number (15% H₂/N₂, Le_f = 0.41). The effect of curvature on flames with high (15% C₃H₈/N₂, Le_f = 1.51) and near-unity (30% CH₄/N₂, Le_f ≅ 1) fuel Lewis numbers is much less.