Laser-based flame species profile measurements: A comparison with flame model predictions

Abstract

Two laser-based diagnostic methods, resonance-enhanced multiphoton ionization (REMPI) and laser-induced fluorescence (LIF), were used for relative concentration measurements of seven species, O, H, OH, CH, CO, HCO, and CH3, in low pressure stoichiometric methaneoxygen, ethyleneoxygen, and ethaneoxygen premixed hydrocarbon flames. For the well-understood methaneoxygen flame, measured relative density profiles for these seven species were in good agreement with flame modeling calculations. This agreement justifies the use of the stoichiometric methaneoxygen flame as a standard of comparison by which relative density profiles, measured for other hydrocarbon flames, may be placed on an absolute density scale. This approach was applied to measurements for the ethyleneoxygen and ethaneoxygen flames. Peak HCO densities for these flames appear to be overstimated by model calculations based on current kinetic models of C1 and C2 chemistry.