喷射方式对直喷汽油分层燃烧的影响研究

利用快速压缩装置进行了喷射方式对直喷汽油分层燃烧的影响研究。研究结果表明 :在当量比小于 0 .5时 ,快速燃烧期保持相同的数值而与喷射方式无关 ;在当量比大于 0 .5时 ,单点喷射方式比双点喷射方式具有较长的快速燃烧期。双点喷射方式的后燃期随当量比的增加而缩短 ,而单点喷射方式的后燃期随当量比的增加而增长。双点喷射方式的燃烧持续期基本上保持一稳定值而不随当量比的改变而变化 ,单点喷射方式下较长燃烧持续期出现在大当量比区域。双点喷射方式由于燃烧持续期短和放热速率快而呈现高的压力升高值。CO在当量比小于 0 .8时具有很低的数值 ,而在当量比大于 0 .8时因强充量分层则随当量比的增加而急速上升。三种喷射方式下碳氢随当量比的增加而增加。双点喷射和单点喷射的 NOx 的最大值分别出现在 0 .6～0 .7和 0 .3～ 0 .5区域处。在当量比小于 0 .8时 ,CO2 不受喷射方式的影响。燃烧效率在当量比 0 .15～ 0 .90范围内均达到 0 .9以上而基本上不随喷射方式而改变

Effect of Injection Modes on Direct Injection Gasoline Stratified Combustion

Effect of injection modes on combustion and emissions of gasoline direct-injection stratified combustion was studied by using a rapid compression machine.The results shows that the rapid burning period remain the same value regardless of injection types when the equivalence ratio φ is smaller than 0.5 and single-injector injection (S.Inj.) shows longer period than that of double-injector injection (D.Inj.) when φ is larger than 0.5.Late burning period decreases with the increase of φ for D.Inj.while it demonstrate an opposite trend for S.Inj.The overall burning period is independent of φ and keeps almost the same value for D.Inj.,whereas longer overall burning period occurs in S.Inj.at the large φ.D.Inj.shows higher value of maximum pressure rise due to short overall combustion duration and fast heat release.CO remains almost zero for all injection modes when φ is smaller than 0.8,and it increases steeply with φ when φ is larger than 0.8 due to the excessive stratification.Unburned hydrocarbons (UHC) increase with the increase of φ for all injection modes.Nox reaches its peak value at the range of φ from 0.6 to 0.7 for D.Inj.and from 0.3 to 0.5 for S.Inj.Injection modes do not affect CO2 when φ is smaller than 0.8.Combustion efficiency maintains greater than 0.9 in the range of φ from 0.15 to 0.9.Little difference in combustion efficiency is observed for all injection modes.