何邦全，赵国兴，李晓，付雪青，张岩.直喷二甲醚在汽油机中压缩自燃特性的试验研究[J].内燃机工程,2019,40(4):85-92.
直喷二甲醚在汽油机中压缩自燃特性的试验研究
Experimental Study on Auto ignition Characteristics of Direct-Injected Dimethyl Ether in a Gasoline Engine
DOI：10.13949/j.cnki.nrjgc.2019.04.013
关键词:二甲醚  燃烧  火焰  内部废气再循环  光学发动机
Key Words:dimethyl ether  combustion  flame  internal exhaust gas recirculation  optical engine
基金项目:国家重点基础研究发展计划项目（2013CB228403）；国家自然科学基金项目(51606175, 51476151)
作者单位
何邦全，赵国兴，李晓，付雪青，张岩 1.天津大学 内燃机燃烧学国家重点实验室，天津 300072；2.中国北方发动机研究所，天津 300405 
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摘要:在一台单缸光学发动机中，利用高速摄像和热力学分析方法，研究了不同缸内残余废气率（iEGR率）下DME喷射时刻(SOI)从曲轴转角-15°变化到-40°过程中自身的燃烧过程。结果表明，在不同iEGR率下，随着SOI提前，燃烧重心前移，燃烧持续期减小，放热率峰值增加，当到达某一特定的SOI值之后，燃烧重心后移，燃烧持续期增加，放热率峰值减小。当SOI在-25°~-15°范围内时，iEGR率32%工况下的燃烧相位迟于iEGR率25%工况，而当SOI为-30°和-40°时iEGR率为32%下的燃烧相位较早。火焰的形态与DME的自燃区域有关。随着SOI提前，初始自燃点逐渐远离喷嘴侧，自燃区域更为分散。在不同工况下，随着瞬时放热率增加，火焰的相对光强增加，用相对光强变化趋势可以表征瞬时放热率的变化。
Abstract:The effects of Dimethyl Ether(DME) injection timing or start of injection(SOI) in the range from -15° to -40° in crank angle at different internal exhaust gas recirculation(iEGR) rates on DME auto-ignition processes were investigated on a single cylinder optical engine using a high speed camera and thermodynamic analysis. The results show that at different iEGR rates, the advance of SOI leas to advanced crank angle of 50% fuel mass fraction burned(CA50), shortened combustion duration and increased peak of heat release rate. However, at a certain SOI, CA50 delays, the combustion duration increases and the peak of heat release rate decreases. In the range of SOI between -15° and -25°, the combustion phase at the iEGR rate of 32% is later than that at the iEGR rate of 25%. At the SOI of -30° and -40°, the combustion phase at the iEGR rate of 32% is much advanced. The flame structure is related to the region of the DME auto-ignition. With the advance of SOI, the initial ignition point moves gradually away from the nozzle, and the combustion zones are more dispersed. Under different operating conditions, the relative flame intensity increases with the increase of the heat release rate, which indicates that the relative flame intensity can characterize the change of heat release rate level.
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