柴油机双喷系统前级SCR的光学诊断  

Optical diagnostic on close-coupled SCR of diesel engine dual-injection system

作　　者：魏锋 王井山 杨海龙 苏菲菲 孙彦斌 贾德民 Wei Feng;Wang Jingshan;Yang Hailong;Su Feifei;Sun Yanbin;Jia Demin(State Key Laboratory of Engine and Powertrain System,Weichai Power Company Limited,Weifang 261061,China)

机构地区：[1]潍柴动力股份有限公司内燃机与动力系统全国重点实验室,潍坊261061

出　　处：《内燃机学报》2025年第2期153-157,共5页Transactions of CSICE

基　　金：泰山产业领军人才工程资助项目。

摘　　要：为了满足柴油机未来排放法规,双喷选择性催化还原(SCR)系统成为一种重要手段,其前级SCR(cc-SCR)截面尿素液滴分布均匀性对NO_(x)的转化至关重要.提出了一种基于粒子图像测速(PIV)光学测试系统和可视化后处理装置的前级SCR截面尿素液滴速度场和液滴浓度分布的快速测试方法,用来评价前级SCR不同配置下的截面液滴分布情况,并进行了验证.结果表明:在1.00 s内,喷射脉宽不足1.00 s时,排气管截面在剩余时间内无液滴,可能会导致低氨储工况下NO_(x)转化效率降低;不同截面位置,二维速度场均呈双旋涡的情况,且仿真与试验结果吻合;在温度为215℃、排气流量为1250 kg/h和360 kg/h条件下,对于不同粒径的喷嘴,其截面尿素液滴分布均匀性取决于排气流量,仿真结果很好解释了这一现象.In order to meet the future emission regulations for diesel engines,dual-injection selective catalytic reduction(SCR)system has become an important means,in which the urea uniformity on the cross section of the close-coupled SCR(cc-SCR)is crucial for NO_(x) conversion.A transparent after-treatment test bench was established and a particle image velocity(PIV)optical method was used to measure the urea droplet velocity field and droplet concentration distribution of the cc-SCR.A computing simulation of the urea distribution was also conducted and validated by the measurement.Results showed that,when the injection pulse width is less than 1.00 s,there has no urea droplets on the cross section of the cc-SCR within 1.00 s,which leads to a decrease of NO_(x) conversion effi-ciency under the condition of low ammonia storage.The velocity field at different cross-sections presents double vortices.The simulation results are found to be consistent with the experimental results.In addition,different noz-zles with different particle sizes were tested on the bench under the temperature of 215℃and the air flow rate of 1250kg/h and 360kg/h,respectively.It is found that the distribution uniformity of urea droplet depends on the exhaust air flow rate.This phenomenon is also well explained through simulation results.

关 键 词：柴油机 后处理 速度场 粒子图像测速 

分 类 号：TK429[动力工程及工程热物理—动力机械及工程]