Effects of the nozzle design parameters on turbulent jet development of active pre-chamber

Active pre-chamber turbulent jet ignition is one of the most promising technologies for developing low- or zerocarbon engines. However, the relevant fundamental studies are far from adequate, particularly for the independent impact of the pre-chamber design parameters on the jet characteristics in the absence of combustion in the main chamber. In this study, the hot turbulent jet characteristics of the pre-chamber fueled with the premixed CH4-air are studied by the double-pass Schlieren imaging. The effects of the pre-chamber nozzle design parameters, including the orifice diameter, total orifice cross-sectional area, and orientation are clarified. The results reveal that the pressure difference between the pre-chamber and main chamber depends on the total orifice cross-sectional area. The effects of the orifice diameter and total orifice cross-sectional area on the penetration rate exhibit a trade-off relation, while the orifice diameter has a more pronounced effect on the hot jet projection area than the total orifice cross-sectional area. Compared to the inclined orifice, the penetration velocity of the straight orifice is faster at the initial hot jet ejection stage. These results are expected to be valuable references for the pre-chamber design and understanding of the ignition mechanisms of active prechamber.