Effects of Orifice Configuration on the Flame Propagation and Mechanism of Jet Ignition under Elevated Temperature and Pressure

In lean burn combustion, jet ignition is such a promising technology that is often used to improve the ignition and enhance combustion stability when ignition failure and misfire might occur. Four different orifice configurations are applied in the fueled pre-chamber and lean main chamber system to investigate the effect of orifice configurations on flame propagation and pressure oscillation. The combustion phases of jet ignition, pressure wave propagation, and mechanism of jet combustion with various orifice configurations considered are presented. In the present work, three phases of jet ignition propagation are observed. Besides, it is found that when the total orifice area is the same, the single-orifice configuration presents the fastest flame propagation and pressure oscillation. The viscosity effect and interactions between jet flows in multi-orifice configurations account for this phenomenon. The two-stage burn in the jet combustion phase, i.e., stoichiometric combustion and lean combustion in the mixing layer, is presented. The former imposes a global heating effect on the lean mixture, while the latter manifests a local influence by sustaining and transferring the flame. In the last section, the end-gas autoignition and pressure oscillation under various orifice configurations is investigated. The present work focuses on the flame propagation and pressure oscillation in an active pre-chamber system, with the underlying mechanism of two-stage combustion explored. In summary, the present work extends the understanding of the flame propagation process in an active pre-chamber system. However, the initial turbulence is ignored in the present work, and further work is supposed to be done to investigate the effect of turbulence inside the pre-chamber.