被动预燃室燃烧策略对汽油机缸内燃烧及排放特性的影响研究

Study on the Influence of Passive Pre-chamber Combustion Strategy on Incylinder Combustion and Emission Characteristics of Gasoline Engines

随着全球排放法规和节能政策日趋严格,汽油机面临巨大挑战,如何实现汽油机高效超低排放成为当前迫切需要解决的技术难题。预燃室湍流射流点火是提高汽油机热效率和降低污染物排放最有前景的技术之一。本文通过耦合详细化学反应机理的三维流动仿真分析,系统研究了稀薄燃烧极限拓展和点火正时对热效率的影响。研究结果表明,被动预燃室相较于火花点火可以有效拓展稀燃极限,提高发动机热效率和降低污染物排放。在过量空气系数为1.5时,最高指示热效率为47.24%,相较于原机提高了11.89%;NOx和Soot较原机也相应减少29.27%和98.76%。

As global emission regulations and energy-saving policies become increasingly stringent,gasoline engines are facing significant challenges.The urgent technical challenge is to achieve high efficiency and ultralow emission of gasoline engines.The pre-chamber turbulent jet ignition is one of the most promising technologies for improving the thermal efficiency of gasoline engines and reducing pollutant emission.In this paper,the influence of lean combustion limit expansion and ignition timing on the optimization of thermal efficiency is investigated systematically through three-dimensional flow simulation analysis coupled with a detailed chemical reaction mechanism.The results show that the passive pre-chamber can effectively expand the lean combustion limit,improve the thermal efficiency and reduce the pollutant emission of the engine in comparison with the spark ignition.At an excess air factor of 1.5,the maximum indicated thermal efficiency is 47.24%,which is 11.89%higher than that of the original engine,with the NOx and Soot reduced by 29.27%and 98.76%,respectively.