柴油机EGR氛围下颗粒微观形貌与结构刚性的分析

发布时间：2017-12-30 18:28

本文关键词：柴油机EGR氛围下颗粒微观形貌与结构刚性的分析　出处：《汽车工程》2016年09期 　论文类型：期刊论文

【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。
[Abstract]:The effects of EGR ratio on the morphology of diesel engine particles and basic carbon particles were studied by scanning, transmission and atomic force microscopy. The variation of physical and mechanical parameters such as elastic modulus and agglomeration force of particles with EGR rate was analyzed. The results showed that the morphology of particles produced by different EGR ratios showed different distribution characteristics, and with the increase of EGR ratio. The particles gradually condensed into clusters, stacked to form peaks, and the size, number and density of the clusters increased gradually. In the core of the basic carbon particles, the flexural structure of carbon layer increases gradually, and the structure of shell carbon layer increases disorderly. With the increase of EGR ratio, the elastic modulus of the particles increases gradually, which indicates that the bonding strength between molecules increases and the structural rigidity of the particles increases gradually, so it is not easy to deform. The main form of agglomeration between particles changed from liquid bridge force to liquid bridge force and van der Waals force, and van der Waals force gradually played a major role, so that the agglomeration force between particles has a large increase. This is also one of the main reasons for the accumulation of particles, the formation of large clusters and the increase of structural rigidity.
【作者单位】：常熟理工学院汽车工程学院;江苏大学汽车与交通工程学院;
【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
【分类号】：U464.172
【正文快照】： 前言近年来,我国大部分地区遭受持续灰霾天气,多个城市大气环境质量达到六级重度污染,空气质量指数(air quality index,AQI)超过500上限[1-2]。统计表明,柴油机排放的NOx和颗粒占机动车总排放的90%以上[3],对灰霾的贡献率约20%[4-5],已成为我国城市空气污染的重要来源。为进一

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