滚流和挤气对汽油机燃烧和性能影响

Effect of Tumble and Squish on Combustion Characteristic and Performance of a Gasoline Engine

采用CFD技术和台架试验手段研究了燃烧室挤气形状及进气滚流对汽油机燃烧特性和性能的影响.结合一台4气门屋脊顶燃烧室结构气道喷射发动机,分别对倾斜挤气/平顶挤气燃烧室、高滚流/低滚流气道组合而成的4种燃烧系统进行了研究.CFD分析表明,低滚流气道与倾斜挤气燃烧室配合,可在压缩冲程上止点附近形成反向挤流并转化为湍动能,这对促进缸内燃烧十分有利.性能试验表明,该方案能加快燃烧速度,并可使点火角提前,改善缸内爆震,同时可提高发动机容积效率,有效提升了性能,发动机燃油耗也有所改善.

Effect of squish pattern of combustion chamber and intake tumble flow on combustion charac-teristic and performance of a gasoline engine is studied using CFD simulation and engine test.Targeting at multiport fuel injection with 4 valves pent-roof combustion chamber,four combustion systems with slant/ flat squish combustion chamber and high/low tumble intake port are analyzed.Results show that for the low tumble intake port with slant squish combustion chamber,the reverse squish flow is formed in the vicinity of top dead center（TDC）,and then it change into the turbulence,which is helpful to the en-hancement of combustion.It is verified by test that this combination can increase combustion speed,allows the advancement of ignition timing and suppresses the knock.The volumetric efficiency is increased with this combination.Engine performance with this combustion system is improved,and fuel consump-tion is reduced.