摘要
采用扫描、透射和原子力显微镜,研究了EGR率对柴油机颗粒和基本碳粒子的微观形貌的影响,分析了颗粒弹性模量和团聚力等物理力学参数随EGR率的变化规律。结果表明,不同EGR率时产生的颗粒形貌呈现出不同的分布特征,随着EGR率增加,颗粒逐渐凝聚成团、堆叠形成山峰状,颗粒的团簇大小、数量和致密程度逐渐增大;基本碳粒子内核的褶皱、弯曲的碳层结构逐渐增多,外壳碳层结构的无序性增加;随着EGR率增加,颗粒的弹性模量逐渐增大,说明分子之间键合强度增加,颗粒的结构刚性逐渐增强,不容易发生形变;颗粒间团聚力的主要作用形式由液桥力向液桥力和范德华力共同作用转变,且范德华力逐渐起到主要作用,使颗粒之间的团聚力有较大幅度增加,这也是导致颗粒发生堆积、形成较大团簇和结构刚性增加的主要原因之一。
The effects of exhaust gas recirculation （EGR） rate on the micro-morphology of particulates and elementary carbon particles in diesel engine are studied with scanning,transmission and atomic force electron micro-scopes ,and the changing law of physico-mechanical parameters including the elastic modulus and cohesive force of particulates with EGR rates is analyzed. The results show that the morphology of particulates generated at different EGR rates exhibits different features of distribution. With the increase of EGR rate,particulates gradually coagulate into clumps or stack into mountain peak-like clusters,the size, number and compactness of particulate clusters gradually increase,the creased and bent carbon layer structures in the core of elementary carbon particle gradually grow,and the disorder of carbon layer structure in the outer shell of elementary carbon particles increases. With the increase of EGR rate,the elastic modulus of particulates gradually rise,meaning the bonding strength between mol-ecules increases,the structure rigidity of particulates strengthens, and particulates are hard to deform. The main form of the action of cohesive force between particulates transforms from liquid bridge force to the coaction of liquid bridge force and Van Der Waals force,and the Van Der Waals force gradually plays the main role,leading to a significant increase in the cohesive force between articulates. This is also one of the main causes of the piling up of particulates,the forming of larger clusters and the increase in structure rigidity.
出处
《汽车工程》
EI
CSCD
北大核心
2016年第9期1052-1057,1085,共7页
Automotive Engineering
基金
国家自然科学基金(51506011和51376083)
江苏省高校自然科学研究面上项目(15KJB470001)
苏州市应用基础研究项目(SYG201515)资助
关键词
柴油机
废气再循环
颗粒
微观形貌
团聚力
diesel engine
exhaust gas recirculation
particulates
micro-morphology
agglomeration force
