柴油射流控制柴油基燃料预混合气压缩着火相位的试验研究

Experimental study on diesel jet controlled compression ignition phase of premixed diesel-based fuels

为了实现对柴油机预混合压缩着火相位的主动控制,提出柴油射流控制柴油基燃料压缩着火方案,并在1台改造的单缸自然吸气186FA柴油机上进行可行性试验研究。研究结果表明:在50%负荷试验条件下,柴油射流可以有效控制预混合气的着火相位;随着柴油射流正时的推迟,10%和50%累积放热对应曲轴转角CA10和CA50均呈线性规律变化,氮氧化物排放明显降低,碳烟排放几乎为零;随着预喷正时的推迟,放热率呈现由单峰较慢放热至双峰放热至最后的单峰快速放热的变化规律,且碳氢化合物和一氧化碳排放逐渐降低;在单峰快速放热情况下,压力升高率最大;增加柴油射流量,燃烧过程减缓,且会扩大柴油的扩散燃烧比例,导致碳烟排放增加。

A jet controlled compression ignition(JCCI)combustion mode was proposed to actively control the combustion phase of premixed charge.In this mode,diesel was used as jet fuel to ignite the premixed diesel-based fuels.Experiments of JCCI were conducted on a modified single-cylinder naturally aspirated 186FA diesel engine.The results indicate that jet-injection of diesel can give a robust control on the combustion phase of premixed charge.Both CA10 and CA50 are in line with diesel jet-injection timings,NOx emissions are reduced with the retarding of jet-injection timing,almost zero soot emissions are measured under these 50%load operating conditions.Heat release rate(HRR)changes from slow with single peak value to double peak values,and finally to fast with single peak value,and both total hydrocarbon(THC)and CO emissions decrease with the retarding of pre-injection timing.The highest maximum pressure rise rate is observed in the cases of fast HRR with single peak value.More diesel jet-injection fuels slow down the rate of combustion process and enlarge the part of combustion controlled by fuel mixing process,resulting in the increase of soot emissions of JCCI combustion.