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在一台火花点燃发动机上分别用几种不同的燃料研究了活塞湿壁对颗粒物的尺寸和质量的影响。利用喷油器探针将已知数量的液体燃料喷到活塞顶上以研究活塞湿壁引起的颗粒生成源。发动机主要以丙烷为燃料运转,同时向活塞顶喷射其他液体燃料。为了研究燃料的挥发性和分子结构对颗粒排放的影响,选择了几种液体燃料。用散射仪确定了颗粒物的排放特性。将散射仪测定的颗粒质量与过滤器称重法测定的结果作了比较,并将散射仪测定的颗粒尺寸与过滤器收集的颗粒SEM(扫描电子显微镜)照片作了比较。发动机以1500r/min 运转,总当量比为0.9,该运转点为Ford 汽车的常用工况。研究所用的液体燃料为加利福尼亚2号汽油、n-正戊烷、异辛烷、甲苯和 n-正十一烷。将液体燃料喷到活塞顶上时产生的颗粒质量明显高于用纯丙烷作燃料或向进气道喷射等量液体燃料时产生的颗粒质量。因受分子结构和挥发性的影响,甲苯和 n-正戊烷产生的颗粒质量最大,颗粒的平均尺寸也最大。颗粒的平均散射直径在500～1000nm 之间。试验中以2s 的时间间隔测定了颗粒随时间变化的排放特性。本研究测定的颗粒质量与以前在相同条件下(如活塞湿壁)测定的未燃 HC 排放量具有很好的相关性。
In a spark ignition engine, several different fuels were used to study the influence of the piston wet wall on the particle size and mass. A known amount of liquid fuel was sprayed onto the piston crown using an injector probe to investigate the source of particle generation caused by the wet wall of the piston. The engine operates mainly on propane fuel while jetting other liquid fuels to the piston crown. In order to study the effect of fuel volatility and molecular structure on particulate emissions, several liquid fuels were selected. The scatterometer was used to determine the emission characteristics of the particulate matter. The mass of the particles measured by the scatterometer was compared with the results of the filter weighing method and the particle size measured by the scatterometer was compared with the particle SEM (scanning electron microscope) photograph collected by the filter. Engine at 1500r / min operation, the total equivalent ratio of 0.9, the operating point for the common Ford car conditions. The liquid fuels used in the study were California No.2 gasoline, n-pentane, isooctane, toluene and n-undecane. The quality of the particles produced when liquid fuel is sprayed onto the piston crown is significantly higher than the mass of particles produced when using pure propane as fuel or injecting an equal amount of liquid fuel into the port. Due to the molecular structure and volatility, toluene and n-n-pentane produce the highest mass and the largest average particle size. The average scattering diameter of the particles is between 500 and 1000 nm. The emission characteristics of the particles as a function of time were measured at 2 second intervals. The particle size measured in this study has a good correlation with the unburned HC emissions previously measured under the same conditions (eg piston wet wall).