基于光学单缸机的含水乙醇汽油直喷燃烧特性分析  

Analysis of direct injection combustion characteristics of hydrous ethanol gasoline based on optical single cylinder engine

作　　者：石秀勇[1] 段毅菲 马骁[2] 张周 康杨 廖延苏 倪计民[1] Shi Xiuyong;Duan Yifei;Ma Xiao;Zhang Zhou;Kang Yang;Liao Yansu;Ni Jimin(School of Automotive Studies,Tongji University Shanghai 201804,China;State Key Laboratory of Automotive Energy Conservation and Safety,Tsinghua University,Beijing 100084,China)

机构地区：[1]同济大学汽车学院,上海201804 [2]清华大学汽车节能与安全国家重点实验室,北京100084

出　　处：《农业工程学报》2020年第5期59-68,共10页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金(51506111);上海市自然科学基金(16ZR1438500)。

摘　　要：含水乙醇与汽油混合能有效改善发动机的燃烧和排放性能,而混合燃料的微观火焰发展能够揭示宏观表现的机理。该研究以此为切入点,采用光学单缸发动机试验,研究了不同喷油策略下,E10W(含水乙醇体积分数为10%)、E20W(含水乙醇体积分数为20%)和E100W(含水乙醇体积分数为100%)3种含水乙醇汽油燃料的燃烧特性、火焰发展及碳烟生成特性。结果表明:正常喷油时,缸压峰值、放热率、火焰传播速度随含水乙醇比例的上升逐渐增大,其中E100W相比E10W缸压峰值增加10%,燃烧相位提前2°CA,火焰传播速度增加15%,燃烧持续期缩短,E100W的循环变动相比E10W下降了20%;推迟喷油后,燃烧相位相比正常喷油时大幅提前,燃烧循环变动增大。火焰发展过程表明,火焰亮度在火焰充满燃烧室以后达到最大,前锋面向燃油湿壁量较高一侧偏置,池火燃烧剧烈区域黄褐色火焰较多,碳烟生成量较高。推迟喷油后缸内火焰分区现象明显,燃烧不均匀现象加剧,池火燃烧明显增多,含水乙醇的添加使火焰传播更均匀,剧烈燃烧池火区域减少,碳烟相对含量可降低90%。因此,缸内直喷汽油机燃用含水乙醇与汽油的混合燃料,可以有效改善发动机燃烧特性,加快火焰传播速度,减少碳烟生成量,对提升直喷汽油机性能和改善颗粒物排放有较好的作用。In recent years, gasoline direct injection(GDI) engines have been promoted worldwide by virtue of its advantages of economy and efficiency, but their particulate emissions are increased significantly compared to port fuel injection(PFI) engines. Ethanol has good research prospects due to its advantages such as high-octane number, low pollution and renewability. At the same time, ethanol has a certain effect on reducing particulate emissions from the engine. The existing research on the application of aqueous ethanol gasoline in GDI engine mainly focuses on the combustion and emission characteristics based on macroscopic characteristics, and there are few microscopic analysis of the flame development and soot formation. On basis of this, this paper studied the cylinder pressure, heat release rate and combustion phase of E10W(10% hydrous ethanol by volume ratio), E20W(20% hydrous ethanol by volume ratio) and E100 W(pure hydrous ethanol) under different fuel injection strategies by optical single cylinder engine test, and analyzed the flame development and soot formation characteristics of the combustion process of hydrous ethanol gasoline. It was found that under the normal fuel injection strategy(start of injection, SOI=-280°CA), the peak value of cylinder pressure and heat release rate gradually increased with the increase of the proportion of hydrous ethanol, the cylinder pressure peak value of E100 W increases by 10% compared to E10 W, while the heat release rate did not increase significantly. The combustion phase angle advanced by 2°CA, the flame propagation speed increased by 15% and the combustion duration was shortened. The combustion coefficient of variation of E100 W was 20% lower than that of the E10 W and E20 W. After delaying fuel injection(SOI=-90°CA), the change of the proportion of hydrous ethanol had no obvious effect on the combustion characteristics. The cylinder pressure peak value of E100 W increased by 5%, the combustion phase was significantly advanced compared with the normal injection,

关 键 词：发动机 燃烧 试验 可视化 含水乙醇 缸内直喷汽油机 碳烟 

分 类 号：TK417[动力工程及工程热物理—动力机械及工程]