Supersonic Combustion Simulation of Cavity-Stabilized Hydrocarbon Flames using Ethylene Reduced Kinetic Mechanism

Hydrocarbons become viable alternatives to hydrogen at Mach numbers below 10, because of greater fuel densities and endothermic cooling capabilities. However, hydrocarbons show difficulties for flame holding under supersonic conditions due to their long ignition delay times. Thus, developing reduced kinetic models that are capable of predicting ignition and blow-out becomes a challenge at scramjet conditions. In the present approach, the fuel molecule breaks-down into CH2O and H2 and a detailed CH2O/H2/O2 reaction subset consisting of 14 species and around 40 reactions is used for accurate predictions. Using this approach reduced kinetic models for ethylene was developed. Also, the application of this reduced kinetic model for scramjet simulation was demonstrated by implementing in a RANS code to predict combustion stability in a cavity flameholder experiments. The reduced model was able predict the stable and lean blowout experimental conditions reasonably well. Also, a six-step ethylene reduced kinetic model is implemented in LES code to predict flame stability at the cavity flameholder experimental conditions.