喷油定时和燃烧室形状对柴油机燃烧及排放的影响  

Effects of Fuel Injection Timing and Combustion Chamber Geometry on Combustion Process and Emissions of Diesel Engine

作　　者：赵昌普[1] 宋崇林[1] 李晓娟[1] 李艳丽[1] 孙强[1] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《燃烧科学与技术》2009年第5期393-398,共6页Journal of Combustion Science and Technology

基　　金：国家重点基础研究发展计划(973)资助项目(2002CB211603);国家自然科学基金资助项目(50676067);中国博士后科学基金资助项目(20070420698)

摘　　要：在保持压缩比不变的条件下,设计了3种不同径深比的燃烧室,并采用CFD数值模拟方法研究了喷油定时和燃烧室形状对柴油机燃烧过程、碳烟和NOx排放的影响.结果表明,随着喷油的推迟,各燃烧室NOx排放均呈下降趋势,碳烟排放则有所增加,尤其是缩口较小的燃烧室,其碳烟生成较多而氧化速率却很低,因此碳烟排放较高.此外,缸内温度为1 500～2 400 K的区域是碳烟生成的主要区域,温度过低不利于碳烟的生成,而较高的温度会促进已生成碳烟的氧化.Three kinds of combustion chambers with different ratios of diameter to depth were designed under the condition of keeping compression ratio of a diesel engine invariable, and the influences of fuel injection timing and combustion chamber geometry on combustion process, soot and NOx emissions of a diesel engine were investigated by using CFD numerical simulation method. The results indicated that, as fuel injection time delayed, NOx emissions of the diesel engine with different combustion chamber bowl geometry decreased and soot emissions increased. In particular, the combustion chamber bowl with a lower ratio of the diameter to depth had a higher soot formation rate and a lower oxygenation rate, leading to the increase of soot emissions. Moreover, the regions with the temperatures of 1500 -2400 K were important sites of soot formation. Too low temperatures were not beneficial to soot formation, while too high temperatures would promote oxygenation of soot.

关 键 词：柴油机 排放 数值模拟 喷油定时 燃烧室形状 径深比 

分 类 号：TK421.2[动力工程及工程热物理—动力机械及工程]