汽车尾部PM2.5排放扩散仿真研究

发布时间：2018-05-02 14:55

本文选题：PM2.5 + 扩散　；参考：《长安大学》2015年硕士论文

【摘要】：PM2.5是我国区域性灰霾天气的重要成因之一,且PM2.5因其粒径小、质量轻、重力小、比表面积大、活性强等特点对人体健康、城市空气质量和能见度影响显著。不同地区的PM2.5源解析研究成果一致认为机动车排放是PM2.5的重要来源之一,所以了解汽车尾气PM2.5的排放扩散特性显得尤为重要。论文采用实验与仿真模型相结合的方法,研究单车尾气PM2.5排放扩散特性。在了解计算流体力学基本理论的基础上进行了车载尾气采集实验,实验以添加95#汽油的东风悦达起亚k2汽车为研究对象,以SEMTECH-EFM3车载尾气流量计、TSI8530粉尘监测仪、干燥管和电脑等为实验工具进行路试直接采样。实验分别采集了怠速、一档10km/h、20km/h、二档20km/h、30km/h、40km/h和三档20km/h、30km/h、40km/h、50km/h下的尾气流量、尾气密度和PM2.5浓度。根据实验得到的数据,经过计算得到尾气排放速度。然后运用CFD软件FLUENT的专用前处理器GAMBIT对汽车排放的物理模型进行简化,建立相应的几何模型并划分网格。接着运用求解器FLUENT进行求解计算。最后对实验结果进行后处理和分析。论文得到如下结论:同一档位下,PM2.5浓度随车速的增大而升高;怠速条件下尾气排放速度最低,但其PM2.5排放浓度略高于一档10km/h和20km/h条件下的值;尾气排放速度对PM2.5扩散有重要影响:同一档位下,随车速的增大,尾气排放速度增大,其扩散范围增大;同一车速下,随档位提高,不利于PM2.5的扩散,容易造成PM2.5积聚;尾气排放方向对PM2.5扩散也有一定影响:与水平方向排放相比,向下倾斜的尾气排放方向有利于PM2.5的沉降,而向上倾斜的尾气排放方向会造成PM2.5长时间的悬浮。
[Abstract]:PM2.5 is one of the important causes of regional haze weather in China, and PM2.5 has a significant effect on human health, urban air quality and visibility because of its small particle size, light weight, small gravity, large specific surface area and strong activity. The results of PM2.5 source analysis in different regions agree that motor vehicle emissions are one of the important sources of PM2.5, so it is very important to understand the diffusion characteristics of vehicle exhaust PM2.5. In this paper, the diffusion characteristics of PM2.5 emissions from bicycle exhaust are studied by combining experimental and simulation models. On the basis of understanding the basic theory of computational fluid mechanics, the vehicle tail gas collection experiment was carried out. The experiment took Dongfeng Yueda K2 vehicle with 9 gasoline as the research object, and took the SEMTECH-EFM3 vehicle exhaust gas Flowmeter TSI8530 dust monitor as the research object. The dry tube and computer were used for direct sampling of road test. The experiment collected the tail gas flow, tail gas density and PM2.5 concentration at idle speed, 10 km / h, 20 km / h, 30 km / h, 40 km / h and 30 km / h / h, respectively, at 30 km / h / h and 30 km / h / h, respectively. According to the experimental data, the exhaust emission rate is calculated. Then the physical model of vehicle emissions is simplified by using GAMBIT, a special preprocessor of CFD software FLUENT, and the corresponding geometric model is established and meshed. Then the solver FLUENT is used to solve the problem. Finally, the experimental results are processed and analyzed. The conclusions are as follows: the concentration of PM2.5 in the same gear increases with the increase of vehicle speed, the exhaust emission rate is the lowest under idle condition, but the PM2.5 emission concentration is slightly higher than that under the first 10km/h and 20km/h conditions. The emission rate of tail gas has an important effect on the diffusion of PM2.5: under the same gear, the speed of exhaust gas emission increases with the increase of the speed of vehicle, and the diffusion range of the tail gas increases with the increase of the speed of the vehicle, and the increase of the speed of exhaust gas with the speed of the same speed is not conducive to the diffusion of PM2.5, and it is easy to cause the accumulation of PM2.5. The direction of tail gas emission has a certain effect on the diffusion of PM2.5: compared with horizontal emission, the downward inclined direction of tail gas emission is conducive to the settlement of PM2.5, while the upward direction of tail gas emission will cause the PM2.5 to suspend for a long time.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X513;X734.2

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