Study on the Effects of Nozzle Layouts of the Passive Pre-chamber on Jet and Combustion Characteristics
The pre-chamber combustion can improve the efficiency of spark-ignition engines and reduce NOx emissions,but the effects of pre-chamber nozzle layouts on jet and combustion are not yet fully unraveled.In this study,a numerical model was established and calibrated based on the Converge three-dimensional simulation software for numerical research.For the passive narrow-throat pre-chamber structure,three nozzle layouts were investigated to uncover their jet characteristics and combustion mechanisms:PC-1 structure with dual-row nozzles,PC-2 structure with only upper-row nozzles,and PC-3 structure with only lower-row nozzles.The research results show that the single-row nozzles structure has higher pre-chamber pressure difference and jet velocity under equivalence or lean conditions,and has higher combustion heat release rate and earlier combustion phase,with PC-2 structure slightly superior especially.The dual-row nozzles structure PC-1 only has higher jet velocity and the earliest combustion phase under ultra-rich conditions.Besides,PC-2 has the lowest heat transfer through the pre-chamber wall,indicating that the heat dissipated in the PC-2 pre-chamber is the lowest,while PC-1 has the highest one.In summary,the pre-chamber with single-row nozzles,especially PC-2,has better combustion characteristics under most practical conditions and is most suitable for engine adoption.
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