复杂街谷结构下污染物传播规律模拟研究

复杂街谷结构下污染物传播规律模拟研究(任务书,开题报告,论文说明书11000字)
摘要
随着城市化进程的加快，人口密度的增加，城市的高楼林立，让高大建筑群围成了“囚牢”，形成了很多街道峡谷。而大量机动车排放的尾气，使街谷内充斥着许多人为废气、大气污染物，难以稀释，构成了街谷内严重的空气环境污染，危害着人们的出行健康。因此，研究复杂街谷结构下的污染物传播与分布规律，为城市中道路高楼的合理布局与规划建设提供科学的依据，对改善人们出行活动的生活环境，实现城市的可持续发展具有重要意义。
本文以一条复杂的典型街道峡谷为研究对象，包括上阶梯型街谷、下阶梯型街谷、等高型街谷以及不同高宽比的街道峡谷。其中在四个递增的风速下，来流风风向垂直于街道峡谷时，街道峡谷内空气的流场和污染物扩散的情况，根据流场和污染物浓度分布总结出复杂的街道峡谷内污染物传播扩散的规律。
本文借助流体力学软件CFD，采用数值模拟的方法，简单的总结出了街道峡谷内污染物流场的分布特点和污染物的传播扩散情况。
本文全面分析了不同结构模型的街道峡谷内污染物的传播，包括上阶梯型街谷、下阶梯型街谷、等高型街谷以及高宽比为1、高宽比为2、高宽比为0.5时街道峡谷内污染物浓度的分布情况。
通过对街谷内污染物浓度分布情况的数值模拟计算结果的认识，发现了当来流风风向垂直于峡谷时，一般情况下，风速越大，街道峡谷内污染物与外界的对流作用越强，污染物的扩散效果越明显，街道峡谷内部的污染物积聚的越少。街道峡谷内上风向背风面一侧近地处污染物的浓度较高，对行人的出行健康最为不利；街道峡谷内污染物对上风向建筑的背风面一侧高处的室内空气环境质量影响相对于其他地方较小，因此该处房间的空气环境最有利于人的活动；在上阶梯型、下阶梯型、等高型街道峡谷模型中，迎风面一侧的污染物浓度始终比背风面一侧低，其中上阶梯型街道峡谷背风面的污染物浓度比其他二者低许多；在常见的三种街道峡谷高宽比尺寸中，当街道峡谷高宽比为1 时街谷内部污染物浓度值最小。
关键词：复杂结构；街道峡谷；污染物扩散；数值模拟

Abstract
With the acceleration of the urbanization process, the increase in population density, the city's tall buildings, so that tall buildings surrounded by a "prison", the formation of a lot of street canyons. And a large number of motor vehicle emissions, so that the streets filled with many people for the exhaust gas, air pollutants, difficult to dilute, constitute a serious air pollution within the street, endangering people's health. Therefore, it is of great significance to improve the living environment of people's travel activities and realize the sustainable development of the city by studying the law of the spread and distribution of pollutants under the complex street structure, and provide the scientific basis for the rational layout and planning and construction of the highway highways in the city .
This article takes a complex typical street canyon as the research object, including the upper ladder valley, the next ladder type street, the contour street and the different aspect ratio street canyon. In the four increasing wind speeds, the flow field and the pollutant diffusion of the air in the street canyon are perpendicular to the street canyon. According to the distribution of the flow field and the pollutant concentration, the pollutants in the complex canal are summarized The law of proliferation.
In this paper, the distribution of pollutant flow field and the spread of pollutants in street canyon are summed up by means of numerical simulation.
This paper comprehensively analyzes the propagation of pollutants in the street canyons of different structural models, including the upper ladder valley, the lower ladder valley, the contour trough and the aspect ratio of 1, the aspect ratio is 2, the aspect ratio The distribution of pollutant concentration in street canyon is 0.5.
Based on the numerical simulation of the distribution of pollutant concentration in the valley, it is found that when the wind direction is perpendicular to the canyon, under normal circumstances, the greater the wind speed, the stronger the convective effect of the pollutants in the street canyon and the pollution The more obvious the diffusion effect of the material, the less the accumulation of pollutants inside the street canyon. The upper reaches of the street canyon to the leeward side of the side of the concentration of pollutants in the vicinity of the higher concentration of pedestrian health is most unfavorable; street canyon pollutants on the wind to the building side of the leeward side of the indoor air environment quality relative to The air environment in the room is the most conducive to human activities. In the upper ladder type, the lower ladder type and the contour street canyon model, the concentration of pollutants on the windward side is always longer than that of the leeward side and the concentration of pollutants on the leeward side of the upper ladder-type canyon is much lower than that of the other two. In the three kinds of street canyon aspect ratios, when the street canyon aspect ratio is 1, The smallest value.
Key words: complex structure; street canyon; pollutant diffusion; numerical simulation

目  录
第1章 绪论    1
1.1研究背景及意义    1
1.1.1课题背景    1
1.1.2研究意义    2
1.2街道峡谷内污染物扩散的研究方法    3
1.2.1现场测试    4
1.2.2物理模型研究    4
1.2.3数值模拟    4
1.3研究历史及现状    4
1.3.1国外研究的历史与现状    4
1.3.2国内研究的历史与现状    6
1.4 课题研究方案设计    8
第2章街道峡谷的模型和数值模拟计算    9
2.1模型的建立    9
2.2污染物扩散的湍流数学模型    10
2.3街道峡谷内污染物扩散的数值模拟计算步骤    11
第3章 街道峡谷内污染物扩散的模拟结果分析    12
3.1 建筑物不同高度对污染物扩散的影响分析    12
3.1.1上阶梯型街道峡谷    12
3.1.2 下阶梯型街道峡谷    13
3.1.3 等高型街道峡谷    14
3.2 街道峡谷不同高宽比与风速对污染物扩散的影响分析    15
3.2.1 理想街道峡谷    15
3.2.2 宽街道峡谷    16
3.2.3 深街道峡谷    17
3.2.4 风速的影响    18
第4章 结论与展望    23
4.1 结论    23
4.2 展望    24
参考文献    25
致谢    28