时序进气柴油机缸内分层与燃烧排放特征数值分析  

In-cylinder Stratification of Gases and Combustion Numeric Investigation of DI Diesel Engine under Sequential-timing Intake Strategy

作　　者：沈照杰[1] 崔文政[1] 刘忠长[2] 韩永强[2] 田径[2] 杨建国[1] 

机构地区：[1]哈尔滨工业大学(威海)汽车工程学院,威海264209 [2]吉林大学动态仿真与控制国家重点实验室,长春130025

出　　处：《农业机械学报》2015年第9期350-355,共6页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家重点基础研究发展计划(973计划)资助项目(2013CB228402);中国博士后科学基金资助项目(2014T70330;2015M571412);哈尔滨工业大学(威海)校科学研究基金资助项目(HIT(WH)201406;HIT.NSRIF.2016095)

摘　　要：缸内再循环废气(EGR)分布是发动机缸内EGR分层燃烧研究的重点与难点,由时序进气策略通过控制进气组分的充气时段来组织缸内EGR分层分布具有重要意义。以高压共轨重型柴油机为研究对象,采用CFD(Computation fluid dynamics)方法建立全参数数值仿真平台,研究不同时序进气组分经过进气及压缩过程后在缸内的分布特征及其对柴油机缸内燃烧及排放的影响。研究中以CO2代替EGR。研究结果表明,时序进气早期进气组分在气缸底部及燃烧室壁面附近分布较浓,后期进气则在气缸中心顶部分布较浓;时序进气能够获得显著的轴向分层分布;与均匀进气相比,缸内压力和温度偏低,燃烧滞后约0.7°CA,但放热率峰值偏高,NOx排放量降低51.2%,碳烟排放量降低13.4%。EGR （Exhaust gas recirculation） in-cylinder distribution to decrease NOx and stratification is a promising solution proposed to control PM （Particular matter ） generation during combustion process. The key issue of EGR stratification is to control in-cylinder distribution. A novel method called timing sequential intake strategy which divides the intake process into several periods and controls different intake charge flows into engine cylinder for each period was proposed and investigated by computation fluid dynamics （CFD） technology. The simulation model was established based on a heavy duty diesel engine. It is indicated that intake charge in earlier intake period was rich at the bottom of combustion chamber while the later charge was rich at the upper center of combustion chamber near compression top dead center. It is feasible to obtain axial stratification using timing sequential intake strategy. The combustion pressure and temperature were lower than those of uniform intake strategy which supplying the mixture of intake CO2 and fresh air during the whole intake process. Compared to the uniform intake strategy, the start of combustion delayed about 0. 7~CA, however, the peak value of heat release rate was much higher, NO~ emissions were decreased by 51.2% , and PM emission was decreased by 13.4%. Timing sequential intake strategy needs to be further investigated as it is beneficial for both reductions of NOx and PM emissions and fuel consumption.

关 键 词：柴油机 废气再循环 缸内分布 时序进气策略 数值模拟 

分 类 号：TK427[动力工程及工程热物理—动力机械及工程]