Modelling Syngas/Air Laser-Induced Ignition with the State-to-State Vibrational Kinetics Taken into Consideration

A thermal nonequilibrium kinetic model for a syngas/air mixture taking into account the state-to-state (STS) vibrational kinetics of CO, N₂, O₂, H₂, and OH molecules is developed. The physical and chemical processes occurring in the mixture when CO molecules are highly vibrationally excited by the absorption of the resonant CO laser radiation are considered. It is shown that the nonequilibrium vibrational excitation of a CO molecule leads to the acceleration of chemical reactions and makes it possible to initiate effectively the combustion of a syngas/air mixture. Due to the radiation absorption and vibrational-chemistry coupling, strongly non-Boltzmann vibrational distributions of the molecules are formed, which significantly influence the syngas combustion kinetics. The results of the STS model are compared with the predictions of simplified models that do not take into account vibrational nonequilibrium or the disruption of local Boltzmann vibrational distributions.