屋顶排放污染物受建筑物下洗效应影响的模拟研究
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摘 要
随着全球和中国经济建设、城市化进程的高速发展，城市人口激增、交通规模
等日益扩大，使得人类和环境之间的矛盾亦越发明显。在城市中由于土地资源的日
益减少，因而伴随着科技进步和建筑施工技术的不断提高，高大的建筑楼群鳞次栉
比地拔地而起，其形状结构也日益多样化。人类活动必然产出特定的排放物，通过
楼顶烟道风口排向大气，各种有害物种融合必然造成对空气的污染，当风遇到高层
建筑物阻挡时, 除大部分向上和两侧穿过外, 还有部分向下带到地面，该现象为建
筑物下洗效应，并使得城市建筑物屋顶烟囱污染物随着气流被带到建筑物近地面，
将对人类的健康产生一定的影响。
本文采用 CFD 数值模拟和风洞模拟相结合的方法，探究不同建筑物布设、
不同建筑物布局、不同污染源（烟囱）位置、不同上游建筑物屋顶形状和高度及
不同下游建筑物高度等因素下，建筑物间的气流运动、污染物浓度分布形式，从
而揭示出屋顶排放污染物受建筑物下洗效应影响下的气流运动和污染物扩散规
律。基于三维不可压缩流动的时均化 N-S 方程、Realizable k-ε湍流模型和污染物
对流扩散方程，建立起城市建筑物间气流运动和污染物扩散的三维数值仿真模
型。在 ANSYS FLUENT 14.0 平台上采用 SIMPLE 算法对所建立的模型进行数值
模拟。
本文通过对三种建筑物布设（四种上游建筑物高度）、 四种污染源位置进行组
合产生的 16 种工况；两种建筑物布局、六种上游建筑物屋顶形状、三种屋顶高度
组合产生的 20 种工况；三个建筑物布局下、不同下游建筑物高度组合产生的 5种
工况进行三维数值模拟。结果表明影响气流运动、旋涡结构、污染物分布与建筑物
布设、建筑物布局、上游建筑物屋顶形状和建筑物高度等都有密切相关：
（1）当上游建筑物高度低于污染源排放所在高度时，污染源位置不会对上游
街谷内污染物分布造成影响，污染随着来流风向下游扩散。当上游建筑物高度高于
污染源所处高度时，随着烟囱位置往下风向移动，污染物越难往上风向扩散，街谷
内污染物浓度水平逐渐降低。当烟囱位置固定，仅 改变上游建筑物屋顶形状时，当
屋顶形状为尖顶时，街谷内的环境会受到巨大的危害，对人体的健康造成隐患。屋
顶形状为圆顶时，街谷内的空气质量不产生巨大的威胁。对于两个建筑物布局和三
个建筑物布局的工况，上游建筑物越高，呈现的浓度分布规律是截然不同的.
（2）不同的下游建筑物 B3高度对于整个计算区域中气流运动和污染物扩散
都有重要影响。两个街谷内纵截面和横截面上污染物分布的规律都一样，分布受到
高度的影响，浓度均是随着高度的增加而先增大后减小。
我们对在建筑物下洗效应影响下，建筑物间污染物扩散分布情况进行的风洞
实验研究中，选择使用点源污染物发放装置，较好地形成了污染物瞬态浓度场激光
片光监测系统，按照设定的实验流程，成功地获得了设计工况的污染物分布图。通
过将建筑物间污染物分布数值模拟及风洞实验两大结果的对比分析，证实数值模
拟结果与风洞实验结果的结论基本一致，与此同时还能够充分证明采用
Realizable k-ε湍流模型，模拟屋顶排放污染物受建筑物下洗效应影响的气流运动
和污染物扩散的规律，是可行并可靠的。
对于未来城市大型楼群建设的布局、结构、高度、排放口设置等规划设计、对
环境监测中科学合理地选择测试点位而言，相信本研究成果具有一定的指导和参
考作用。
关键词：屋顶烟囱 屋顶形状 建筑物高度 下洗效应 数值模拟 污染物
扩散 风洞实验
ABSTRACT
With the rapid development of global and China's economic and urbanization,
population explosion and expansile traffic scale lead to the increasingly obvious conflicts
between humans and the environment. Due to the diminishing land resources in the city
and new construction technology skills applied, the tall buildings are springing up and
their shape and structure are diversified. Specific emissions inevitably produced by
human activities and are emitted through the stack on the roof into the atmosphere. A
variety of harmful pollutants will cause the air pollution. When blocked by tall buildings,
parts of the wind goes upward and across both sides and some sinks to ground. This is
called downwash effect, which makes the city building roof with chimney polluted air
brought to the building near the ground, and it will produce some effects on human health.
In this paper, a method of combining wind tunnel experiments and CFD simulations
is used to explore the factors such as different building configurations, layouts of
buildings, various pollution source locations, different roof shapes and heights of the
upstream building and various heights of downstream building that how they affect the
airflow and pollutant dispersion between the buildings in oder to reveal the influence of
roof pollutant exhausts by building downwash effects. A three-dimensional CFD model
for evaluating the flow and pollutant dispersion was built up, which was based on the
incompressible N-S equations, realizable k-ε turbulence model and the pollutant
transportation equation. The numerical simulations of the model were conducted on
ANSYS FLUENT 14.0 with SIMPLE scheme applied.
In this study, 16 cases are composed of two effect factors. They are different
configurations of buildings (four kinds of upstream building’s height) and four kinds of
pollution source location. Another 20 cases are composed of there factors which are two
layouts of building, six kinds of roof shape and three kinds of roof height of upstream
buildings. Finally 5 cases of different heights of downstream building under three
buildings’ layout situation. The results showed that the air flow, vortex structure, the
pollutant distribution are closely related to the configuration and layout of buildings, roof
shape and height of upstream building and the building height:
(1) When the upstream building height is lower than the downstream’s, the pollution
location will not affect the pollutant distribution inside the upstream canyon and
pollutants will spread with wind direction to downstream. When the upstream building
height is taller, the distribution will be affected. When the location moves downward, the
pollutant is hard to dilute in upper air and the pollutant concentration level gradually
reduces down inside canyon. When the pollution location is fixed and the roof shape is
steeple, it will do a great harm to environment and hazard to body health in the street
canyon. When roof shape is dome, it is friendly to environment. When the upstream
building is higher, the concentration distribution law is very different for the layout of
two buildings or three buildings’ case.
(2) Different downstream building (B3) heights make significant influence to the air
flow and pollutant diffusion in the entire computing area. The distribution law in two
canyons on both longitudinal and transversal surface is same. The distribution is affected
by the downstream building height: the concentration is first increased and then
decreased with the increase of building height.
A point source distribution attached to the large environmental wind tunnel were
applied, and a light-monitoring system in the transient laser sheet for pollutant
concentration was formed in the wind tunnel experiment for researching the distribution
of pollutant between the buildings affected by downwash effect. The concentration
distribution figures of some cases are obtained followed the designed experiment process.
On this comparison and analysis of simulation and wind tunnel results, the numerical
simulation results were in conformity with those of wind-tunnel experiment in a variety
of conditions. Meanwhile we also find that the numerical simulation results simulated by
realizable k-ε turbulence model were feasible and reliable. This research is believed that
it has certain guidance and reference for design on layout, structure, height and
configuration of future urban tall buildings group and scientific selection of the test points
in the environmental monitoring.
Key Word: stack, roof shape, building height, downwash, CFD,
pollutant dispersion, wind tunnel experiment
目 录
中文摘要
ABSTRACT
第一章 绪 论 .................................................................................................................. 1
1.1 课题的研究背景 .................................................................................................... 1
1.1.1 全球大气污染现状 .......................................................................................... 1
1.1.2 中国所面临的环境现状与趋势 ...................................................................... 1
1.1.3 课题研究的背景 .............................................................................................. 6
1.2 本课题国内外研究的现状与方法 ......................................................................... 6
1.2.1 国内外研究现状 .............................................................................................. 6
1.2.2 研究方法 .......................................................................................................... 7
1.3 本论文的目的、意义及主要内容 ........................................................................ 11
1.4 本论文的创新点 .................................................................................................. 12
第二章 建筑物下洗效应的计算流体动力学理论基础 .............................................. 13
2.1 建筑物下洗效应简介 .......................................................................................... 13
2.2 计算流体动力学（CFD）理论基础 .................................................................. 13
2.2.1 网格技术 ........................................................................................................ 14
2.2.2 控制方程 ........................................................................................................ 15
2.2.3 湍流模型 ........................................................................................................ 16
2.2.4 污染物对流扩散方程 .................................................................................... 19
2.2.5 边界条件的设置 ............................................................................................ 20
2.2.6 微分方程的离散和求解 ................................................................................ 21
2.3 本章小结 .............................................................................................................. 23
第三章 CFD 模型验证与分析 ..................................................................................... 24
3.1 加拿大肯高迪亚大学风洞实验介绍 .................................................................. 24
3.2Chavez 所做数值模拟的介绍 ............................................................................... 26
3.3 验证模型参数设置 ............................................................................................... 26
3.3.1 物理模型 ........................................................................................................ 26
3.3.2 数学模型 ........................................................................................................ 27
3.4 验证结果 ............................................................................................................... 28
3.5 本章小结 ............................................................................................................... 30
第四章 不同建筑物布设下下游建筑物屋顶烟囱布局对气流运动与污染物扩散的
CFD 研究 ....................................................................................................................... 31
4.1 物理模型与计算区域 .......................................................................................... 31
4.1.1 不同的建筑物布设 ........................................................................................ 31
4.1.2 不同的烟囱布局 ............................................................................................ 31
4.1.3 计算区域 ........................................................................................................ 32
4.2 CFD 模拟 .............................................................................................................. 33
4.2.1 网格划分 ........................................................................................................ 33
4.2.2 边界条件 ........................................................................................................ 33
4.2.3 求解方法 ........................................................................................................ 33
4.3 数值模拟结果与分析 .......................................................................................... 34
4.3.1 相同建筑物布设下烟囱布局对气流运动与污染物扩散的影响 ................ 34
4.3.2 相同烟囱布局下建筑物布设对气流运动与污染物扩散的影响 ................ 52
4.3.3 下洗效应的危害 ............................................................................................ 54
4.4 本章小结 .............................................................................................................. 54
第五章 上游建筑物屋顶形状与高度对气流运动与污染物扩散影响的 CFD 研究 57
5.1 物理模型与计算区域 .......................................................................................... 57
5.1.1 物理模型 ........................................................................................................ 57
5.1.2 计算区域 ........................................................................................................ 57
5.2 两个建筑物情况下各工况的数值模拟结果与分析 .......................................... 58
5.2.1 相同上游建筑物高度在不同屋顶形状下对污染物扩散的影响 ................ 59
5.2.2 相同上游建筑物屋顶形状在不同高度下对污染物扩散的影响 ................ 67
5.3 三个建筑物情况下各工况的数值模拟结果与分析 .......................................... 70
5.3.1 相同上游建筑物高度在不同屋顶形状下对污染物扩散的影响 ................ 71
5.3.2 相同上游建筑物屋顶形状在不同屋顶高度下对污染物扩散的影响 ........ 79
5.3.3 不同下游 B3建筑物高度对于污染物扩散的影响 ...................................... 83
5.4 本章小结 .............................................................................................................. 91
第六章 建筑物下洗效应的风洞实验和数值模拟结果与风洞实验结果的对比 ...... 94
6.1 风洞简介 .............................................................................................................. 94
6.1.1 我校环境风洞简介 ........................................................................................ 94
6.2 风洞实验 ............................................................................................................... 97
6.2.1 实验目的与意义 ............................................................................................ 97
6.2.2 实验装备配置 ................................................................................................ 98
6.2.3 实验方法 ........................................................................................................ 99
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作者：侯斌
分类：高等教育资料
价格：15积分
属性：123 页
大小：12.03MB
格式：PDF
时间：2025-01-09
