Comparative Study of the Effects of Nitrous Oxide and Oxygen on Ethylene Ignition

To explore the effects of N2O and O2 on C2H4 ignition, ignition delay times of stoichiometric C2H4/O2/N2O/Ar mixtures with mole blending ratios of N2O/(N2O + O2) = 0, 50, 80, and 100% were measured in a high-pressure shock tube. Reflected shock conditions cover a range of pressures from 1.2 to10 atm and temperatures from 1090 to 1760 K. In addition, ignition delay times of C2H4/N2O/Ar mixtures are measured at pressures of 1.2–10 atm, equivalence ratios of 0.5–2.0, and temperatures of 1214–1817 K. The results indicate that, in the studied conditions, the ignition delay times of C2H4 greatly increase as the N2O concentration increases at a given pressure and temperature. Five recent literature models are tested against the new measured ignition delay times and show very small discrepancies among each other for the C2H4/N2O/Ar mixtures but exhibit significant discrepancies for the C2H4/N2O/O2/Ar mixtures. Moreover, the kinetic analysis is performed to reveal the reason for the discrepancies among the five models and to investigate the different effects of N2O and O2 on the C2H4 ignition.