High-temperature oxidation of acetylene by N₂O at high Ar dilution conditions and in laminar premixed C₂H₂ + O₂ + N₂ flames

High-temperature oxidation of acetylene (C₂H₂) is studied behind reflected shock waves and in laminar flames. Atomic resonance absorption spectroscopy (ARAS) is employed to record oxygen atom concentration profiles for the mixture of 10 ppm C₂H₂ + 10 ppm N₂O + argon and temperatures from 1688 K to 3179 K, extending the range of such data available from the literature. Laminar burning velocity of C₂H₂ in a diluted oxidizer with 11–13% O₂ in the O₂ + N₂ mixture is measured using the heat flux method and compared to the literature data for the 13% O₂ mixture. An updated detailed kinetic mechanism is presented to model and analyze the results, and the selection of rate constants in the C₂H₂ sub-mechanism, whose importance was identified by the sensitivity analysis, is discussed. The performance of the new model is compared against several reaction schemes available from the literature, and kinetic differences between them are outlined. The new shock-wave data helped to improve the performance of the present model compared to its previous version. For the laminar flames, a particular importance of reactions involving C₂H₃ is identified, however, the reasons for the observed differences in model predictions are to a large extent located outside the C₂H₂ sub-mechanism, which were also identified.