OH and C2H4 species time-histories during hexadecane and diesel ignition behind reflected shock waves

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 1373K and a pressure range of 4–7atm. Initial fuel concentrations varied between 150 and 1800ppm with equivalence ratios between 0.4 and 2, and were determined using 3.39μm He–Ne laser absorption. OH concentration time-histories were measured using absorption of frequency-doubled ring-dye laser radiation near 306.7nm. Ethylene time-histories were measured using absorption of CO2 gas-laser radiation near 10.5μm. 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.