Numerical analysis of the development and propagation mechanism of the methane turbulent jet flame

This study aims to investigate the characteristics and development mechanisms of the turbulent jet flame generated by a pre-chamber. A numerical simulation model is established using the large-eddy simulation (LES) turbulence model and the partially stirred reactor (PaSR) combustion model based on experimental data from a constant-volume combustion vessel. The development and propagation mechanisms of methane turbulent jet flames are systematically investigated, and the effects of pre-chamber equivalence ratio (Φ = 0.9–1.2) and nozzle diameter (D = 3.65–9.125 mm) on turbulent flame behavior are further analyzed. The findings reveal that turbulent jet flame development is mainly governed by the interaction between the cold jet flow and the developing flame front. Stable propagation begins after flame broadening and the formation of a high-temperature jet head with complex vortex structures, after which flame propagation is primarily driven by the pressure difference between the pre-chamber and main chamber. The well-developed high-temperature jet head provides favorable ignition conditions for the main chamber. Using a slightly rich pre-chamber mixture (Φ = 1.1) and a larger nozzle diameter (D = 9.125 mm) effectively suppresses unstable flame propagation, providing a basis for the selection of pre-chamber operating parameters and nozzle geometry.