A Simplified Kinetic Model for Large Eddy Simulation of Ethylene Supersonic Combustion

The simplified kinetic model is significant for large eddy simulation (LES) of ethylene supersonic combustion. In this study, a simplified kinetic model for ethylene with 23 species and 40 reactions is developed via a simplified strategy of adding sensitivity reactions to an extremely simplified kinetic model. The ignition delay time is in the typical pressure range of a supersonic combustor with equivalence ratios of 0.3, 0.5, 1.0, and 2.0. The laminar flame speed is at equivalence ratios of 0.4–2.0 with unburned temperatures of 298–470 K and pressures of 1–10 atm. The temperature and species profiles are at equivalence ratios of 0.5 and 0.7. The predictions of the developed model are in good agreement with the experimental data over a wide range of comparisons. Sensitivity analysis is also performed at an equivalence ratio of 0.5, as well as flux analysis for the pre-ignition regime. The developed model is incorporated into two experimental models of supersonic combustion for LES. The computational results in the cold flow field are in very good agreement with the experimental data and in the combustion flow field agree quite well with the experimental data until downstream of the expansion section. Numerical schlieren compared to experimental schlieren shows that the flow field details are captured quite well, including vortex and wave system structure. However, in the combustion flow field, the problem of insufficient heat release due to the sharp reduction in the reactions of the kinetic model is still reflected in the shock position and pressure data.