Reply to the letter of D. Gutman

Abstract

The first simultaneous multi-species laser absorption time-history measurements for OH and C2H4 were acquired during the oxidation of n-hexadecane and commercial diesel fuel (DF-2). The experiments were performed behind reflected shock waves in a new second-generation aerosol shock tube over a temperature range of 1120K to 1373 K and a pressure range of 4–7 atm. Initial fuel concentrations varied between 150 and 1800 ppm with equivalence ratios between 0.4 and 2, and were determined using 3.39 μm He–Ne laser absorption. OH concentration time-histories were measured using absorption of frequency-doubled ring-dye laser radiation near 306.7 nm. Ethylene time-histories were measured using absorption of CO2 gas-laser radiation near 10.5 μm. Comparisons are given of these species concentration time-histories with two current large n-alkane mechanisms: the LLNL-C-16 mechanism of Westbrook et al. [13] and the JetSurF C-12 mechanism of Sirjean et al. [14]. Fair agreement between model and experiment is seen in the peak ethylene yields for both fuels; however, modeled early time-histories of OH, an important chain-branching species, differ significantly from current measurements.