Quantitative oxygen atom measurements in lean, premixed, H2 tubular flames

Abstract

Quantitative O-atom profiles are measured for the first time in tubular flames and used to assess the performance of chemical kinetic mechanisms in tubular flame simulations. Atomic oxygen is measured via femtosecond, Two-Photon Laser Induced Fluorescence (fs-TPLIF) to avoid photolytic interference. The fs- TPLIF signal is corrected for collisional quenching from major species concentrations measured by Raman scattering. Temperature-dependent quenching rate in the form of T ^−0.5 for H2O is applied to better represent the actual physics, and all simulations are found to agree with this method. Atomic oxygen is reported in H2/O2 flames diluted with N2 or CO2 at 200 and 400 s ^−1 stretch rates. The oxygen radical data is compared to predictions using three different, detailed chemical kinetic mechanisms. Predictions of profile shape vary slightly, but the peak O-atom number density is calculated within experimental uncertainty by each mechanism.