汽油/柴油双燃料不同HPCC燃烧模式的数值模拟  

Numerical Simulation of Different Gasoline/Diesel Dual-Fuel HPCC Combustion Modes

作　　者：李逾[1] 郑尊清[1] 杨彬彬[1] 尧命发[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》2014年第6期546-552,共7页Journal of Combustion Science and Technology

基　　金：国家杰出青年科学基金资助项目(51125026)

摘　　要：针对汽油/柴油双燃料高比例预混燃烧(HPCC)模式,在总喷油量、主放热时刻(CA50)基本相当的条件下,对柴油早喷(E-HPCC)与柴油晚喷(L-HPCC)情况下的燃烧特性和排放特性进行了数值模拟研究.结果表明,HPCC着火和燃烧过程主要受缸内活性自由基控制,较晚喷射会导致缸内局部正庚烷浓度高、活性较大,造成高温放热提前;较早喷射正庚烷会抑制低温放热,从而增加着火时刻缸内活性自由基的数量,是放热率较高、最大压升率较大的主要原因.L-HPCC模式下,高温放热时刻缸内局部正庚烷浓度较大造成了缸内局部温度较高,促进了NOx生成,相对E-HPCC模式NOx排放较高;虽然L-HPCC局部浓度较高会促进碳烟的生成,但同时较高的燃烧温度加强了碳烟的氧化,因此L-HPCC模式的碳烟排放低于E-HPCC模式.Based on gasoline/diesel dual-fuel highly premixed compression combustion（HPCC）mode,this paper carries out numerical simulation of the effect of early-injection and late-injection on combustion and emission characteristics,keeping injection mass and combustion phasing almost the same.The study shows that the ignition and combustion process of HPCC are mainly controlled by reactive radicals,i.e.,late-injection increases the local n-heptane concentration and reactivity,resulting in early heat release;early-injection restrains low temperature heat release,increasing the amount of reactive radicals,resulting in high heat release rate and maximal pressure rise rate.In LHPCC mode,higher local concentration of n-heptane increases local temperature,and promotes NOx generation resulting in higher NOx emission then E-HPCC mode;however,higher local temperature promotes both soot generation and consumption,resulting in lower soot emission than E-HPCC mode.

关 键 词：高比例预混合燃烧 低温燃烧 化学动力学 数值模拟 

分 类 号：TK442[动力工程及工程热物理—动力机械及工程]