Simulation of supersonic Ethylene–Hydrogen and air auto-ignition flame using skeletal mechanism

Three ethylene–air combustion mechanisms were validated against detailed mechanism USC-Mech II, and the results showed that the three mechanisms were not appropriate for combustion of ethylene–hydrogen/air. A 38-species skeletal mechanism was developed for ethylene–hydrogen/air based on the detailed mechanism USC-Mech II. A good agreement is found between the skeletal mechanism and the detailed mechanism in terms of the ignition delay time and the laminar flame speed over a wide range of parameters. After the computational methodology was validated with a supersonic hydrogen–air auto-ignition flame, the skeletal mechanism was employed to simulate the auto-ignition of ethylene–hydrogen mixtures in a hot supersonic airflow. The results showed satisfactory agreement with experimental data, which demonstrates that the skeletal mechanism could reasonably predict the ignition position. An analysis of the flame structure was conducted with respect to the distributions of the species, heat release, pressure, and temperature. Investigations into various parameters revealed that auto-ignition occurred in the most reactive mixture fraction with the minimum ignition delay time rather than the stoichiometric mixture fraction during supersonic combustion.