The impact of methane oxidation kinetics on a rocket nozzle flow

The impact of methane combustion kinetics on a rocket nozzle flow is theoretically studied in the work. To evaluate the effect of the kinetics, simulations of a rocket nozzle flow are carried out using the computational fluid dynamics solver Fluent. At first, a methane kinetic model is selected. The comparison of different kinetic models shows that the recent skeletal mechanism of Zhukov and Kong has a very good accuracy at a small size. For comparison, the flow simulations are performed both for hydrogen/oxygen and methane/oxygen propellant combinations, and for three different reaction models: non-reactive ("frozen") flow, reactive (non-equilibrium) flow, and chemically equilibrium flow. Chemically non-equilibrium flow is modelled using the Zhukov-Kong model. Simulations results show that the recombination reactions of combustion products should be taken into account for modelling rocket nozzle flow. For hydrogen the difference in results between chemically non equilibrium and equilibrium flows is negligible while in methane the difference is small but noticeable.