建筑物布局与隔墙对街道峡谷内污染物扩撒影响的数值仿真研究

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摘要

随着中国城市化进程的加快，建筑物不断密集化，汽车保有量与日俱增，汽

车排放的尾气污染日益严重，人民生活质量受到了很大的影响。尤其近些年，随

着车辆数量急剧增加，机动车尾气排放已成为我国大城市中空气污染的主要来源。

机动车排放污染物在街道周围的扩散主要受街道两侧建筑物周围的流场所控

制，而该流场主要受街道布局的影响，街道峡谷是其中一种典型的街道布局形式。

街道峡谷内机动车尾气对机动车驾驶员、乘客、行人以及道路两侧居民等人的身

体健康带来直接危害。由于机动车尾气排放已成为大都市中空气最主要的污染来

源，使得街道峡谷内污染物对流扩散问题已成为环境工程领域研究的热点。

本文采用数值模拟的方法，探究了不同建筑物布局、上游建筑物的不同宽度、隔

离墙对街道峡谷内的气流旋涡运动特征和污染物扩散分布的影响，揭示出了相应

的峡谷内气流运动和污染物扩散的影响规律。

基于二维不可压缩流动的时均化 N-S 方程、湍流模型和污染物对流扩散方程，

构建起模拟街道峡谷内气流运动和污染物扩散的数学模型，并利用德国汉堡大学

风洞实验数据对所建模型进行了验证。研究表明，数值模拟结果与风洞实验数据

非常接近（对于城市街道峡谷工况，数值模拟结果和风洞实验结果的平均误差、

最大误差和最小误差分别为 7.6%、16.4%和0.3%；对于孤立街道峡谷工况，数值

模拟结果和风洞实验结果的平均误差、最大误差和最小误差分别为 8.0%、16.1%

和0.2%）。

采用验证过的 CFD 模型，模拟了 10 种不同情况下的孤立街道峡谷内气流运

动和污染物扩散。计算得到的气流速度场和污染物扩散分布图表明峡谷内气流旋

涡结构和污染物分布与上游建筑物宽度、建筑物布局密切相关：（1）随着上游建

筑物宽度的增加，街道峡谷内的漩涡中心位置向下偏移，导致街道峡谷内速度变

大；（2）当 W/H=0.5，1.0，2.0（W是上游建筑物的宽度，H是建筑物的高度），

上游建筑物屋顶上方形成回流区，区域覆盖了整个建筑物屋顶；但当 W/H=2.5，

3.0 时，气流会再次附着在上游建筑物屋顶；（3）当上游建筑物的宽度小于临界宽

度（W=2H）短时，增加上游建筑物宽度将导致背风面污染物浓度相应的增加，上

游建筑物屋顶污染物的浓度随之减小；（4）当上游建筑物的宽度大于临界宽度时，

上游建筑物屋顶的污染物浓度及其的小，可以忽略不计，并且背风面的污染物浓

度几乎不因增加上游建筑宽度而受影响；（5）当建筑物放在峡谷的逆风向（上风

向）时，气流会附着在上游建筑物屋顶上，于是上游建筑物屋顶上污染物浓度很

小，几乎可以忽略不计；（6）增加上游建筑物个数时，街道峡谷内污染物浓度以

及上游建筑物屋顶的污染物浓度显著增加，而下游建筑物屋顶的污染物浓度非常

小。

采用验证过的 CFD 模型，同样模拟了 9种不同情况下的城市街道峡谷内气流

运动和污染物扩散。模拟结果表明城市街道峡谷内气流旋涡结构和污染物分布与

隔离墙密切相关：（1）当隔离墙的高度是 0.5m 时，对于上游建筑物背风面，污染

物浓度有所减小，下游建筑物的迎风面上污染物浓度有所增加；（2）当隔离墙的

高度增加到 0.8m，在峡谷的背风面、迎风面的污染物浓度都有所增加；（3）街道

峡谷宽度变宽，进入街道峡谷里的空气通量变大，空气速度也随着变大，污染物

迅速的扩散出去，街谷内的污染物浓度相应的减少；（4）在街道峡谷中间添加一

个隔离墙，隔离墙充当挡板的作用，使得背风面、迎风面污染物浓度都增加；当

在靠近左右人行道附近各加一个墙的时候，街谷背风面、迎风面污染物浓度变化

不大；当放置三个墙的时候，峡谷迎风面几乎不变，有略微增加，背风面有所减

少。

本研究成果对于城市道路建筑布局设计、环境监测中科学合理布设测试点位

置以及预测街道峡谷内的空气质量等具有指导意义。

关键词：街道峡谷建筑物布局隔离墙气流运动污染扩散数

值模拟

ABSTRACT

As China's urbanization process accelerated, buildings densely and increasing car

ownership, which made the exhaust pollution becomes more and more serious, people's

quality of life are affected seriously. Especially in recent years, along with the number

of vehicles increase sharply, motor vehicle exhaust emission has become the main

source of air pollution in big cities in China.

The dispersion of atmospheric pollutants in urban environments depends on the

turbulent airflow around complex building structures. Street canyon is one typical

configuration, within street canyons, the pollutants emitted from motor vehicles have a

direct impact on the health of the drivers, passengers, pedestrians, and residents nearby.

Since traffic is accepted to be a major emission source of air pollutants in urban areas,

investigations of dispersion processes in street canyons have become a focal point in

environment research. This study used numerical simulation methods, analyzing a large

number of numerical dates, investigating the effect of upstream building width, upwind

building configuration and low boundary wall on wind flow and pollutant dispersion in

street canyons.

Based on the Reynolds Averaged Navier-Stokes equations coupled with the

standard



k

turbulence model and the transport equation for pollutant concentration,

a two-dimensional numerical model for evaluating airflow and pollutant dispersion

inside an urban street canyon is firstly developed using the FLUENT code, and then

validated against the experimental data obtained from a detailed wind tunnel study by

Meroney in Hamburg University. It was found that the model performance is

satisfactory (for urban street canyon, the mean, maximum and minimum relative

deviations between the numerical and experimental results are 7.6%、16.4% and 0.3%,

respectively; for isolate street canyon, they are 8.0%、16.1 and 0.2%).

Using established CFD model, 10 kinds of situations on airflow and pollutant

dispersion within an isolated street canyon is investigated numerically. The computed

air velocity vector fields and pollutant concentration contours indicate that the

in-canyon vortex dynamics and pollutant distribution patterns depend on the upstream

building width, upwind building configurations strongly: (1) the location of in-canyon

vortex center shifts downwards as the upstream building width increase; (2) the

recirculation zone above the upstream building roof covers the whole building roof for

W/H=0.5,1.0,1.5 and 2.0 (W is the upstream building width and H is the building height)

case whereas the flow reattaches the upstream building roof for W/H=2.5 and 3.0 cases;

(3) when the upstream building width is shorter than the critical width Wc(=2H),

increase of the upstream building width leads to increase of pollution level on the

leeward wall and to decrease of roof-level concentration at the upstream building; (4)

when the upstream building width is longer than the critical width, the roof-level

concentrations at the upstream building roof are negligibly small, and the pollution level

on the leeward wall is almost unaffected by further increasing the upstream building

width; (5) when building are placed upwind of the canyon, the flow attaches the

upstream building roof and thus the roof-level concentrations at the upstream building

are negligibly small; (6) the pollution levels inside the canyon and on the downstream

building roof increase significantly with the number of upwind buildings.

Using established CFD model, 9 kinds of situations within an urban street canyon

is investigated numerically. And the computed air velocity vector fields and pollutant

concentration contours also indicate that the in-canyon vortex dynamics and pollutant

distribution patterns depend on the wedge-shaped roof configurations strongly: (1)

when the height of the low boundary wall is 0.5m, the concentration of the leeward is

decreased, while the concentration of windward is increased; (2) when the height of low

boundary wall is 0.8m, both the concentration of leeward and windward are increased;

(3) when the width of the canyon is longer, the air flux has increased, the velocity

increased too, which made the concentration of pollution decreased; (4) when put one

low-boundary wall in the canyon, the wall worked as a baffle, which made the

concentration of leeward and windward increased; when put two walls between footpath

and driveway, the change of the concentration are negligibly small; when put three walls

on the canyon, there’s little decrease in leeward, while the change on the windward is

negligibly small.

The results of this study have directive signigficance on some fields, which include

the layout of urban road construction, setting a scientific and rational test point location

in the environmental monitoring ,and forcasting the air qualities of street canyons.

Key word: Street canyon, building configuration, low boundary wall,

airflow, pollutant dispersion, numerical simulation

中文摘要

ABSTRACT

第一章绪论 .................................................................................................................. 1

1.1 课题研究的背景 .................................................................................................... 1

1.1.1 空气污染现状 ................................................................................................. 1

1.1.2 街道峡谷内空气污染现状 ............................................................................. 2

1.1.3 污染物扩散的影响因素 ................................................................................ 3

1.2 国内外研究现状 .................................................................................................... 4

1.3 问题的提出 ............................................................................................................ 8

1.4 论文的目的、意义及主要内容 ............................................................................ 9

1.4.1 研究的目的、意义 ........................................................................................ 9

1.4.2 研究的主要内容 ............................................................................................ 9

1.5 论文的创新点 ...................................................................................................... 10

第二章街道峡谷内气流运动和污染物扩散的理论基础以及 CFD 模型的构建 ..... 11

2.1 街道峡谷简介 ....................................................................................................... 11

2.2 CFD 模型 .............................................................................................................. 13

2.2.1 气流运动控制方程 ...................................................................................... 13

2.2.2 污染物对流扩散方程 .................................................................................. 16

2.2.3 计算区域和边界条件 .................................................................................. 17

2.2.4 网格划分 ...................................................................................................... 19

2.2.5 数值算法 ...................................................................................................... 21

2.2.6 模型验证 ....................................................................................................... 21

第三章建筑物宽度对街道峡谷内污染物扩散的影响 .............................................. 23

3.1 模拟计算所采用的孤立街道峡谷几何结构形态 .............................................. 23

3.2 CFD 模型 .............................................................................................................. 25

3.3 模型验证 .............................................................................................................. 26

3.4 数值模拟结果及分析 .......................................................................................... 28

3.4.1 流场计算结果分析 ...................................................................................... 28

3.4.2 污染物扩散的计算结果分析 ....................................................................... 31

3.4.3 近地面污染物扩散分析 .............................................................................. 33

3.5 本章小结 .............................................................................................................. 34

第四章建筑物布局对街道峡谷内污染物扩散的影响 .............................................. 35

4.1 模拟计算所采用的几何结构形态 ...................................................................... 35

4.2 CFD 模型 .............................................................................................................. 36

4.3 数值模拟结果及分析 .......................................................................................... 36

4.3.1 流场计算结果分析 ...................................................................................... 36

4.3.2 污染物扩散的计算结果分析 ...................................................................... 38

4.3.3 近地面污染物扩散分析 ............................................................................... 40

4.4 本章小结 .............................................................................................................. 40

第五章隔离墙对街道峡谷内污染物扩散的影响 ...................................................... 42

5.1 模拟计算所采用的城市街道峡谷几何结构形态 .............................................. 42

5.2 CFD 模型 .............................................................................................................. 43

5.2.1 网格划分以及敏感性分析 .......................................................................... 44

5.2.2 计算区域和边界条件 .................................................................................. 45

5.3 模型验证 .............................................................................................................. 46

5.4 数值模拟结果及分析 .......................................................................................... 48

5.4.1 隔离墙高度的影响 ...................................................................................... 48

5.4.2 建筑物与街道宽高比（H/W）的影响 ...................................................... 53

5.4.3 墙个数的影响 .............................................................................................. 55

5.4.4 污染源发放位置的影响 .............................................................................. 59

5.4.5 近地面污染物浓度图 .................................................................................. 62

5.5 本章小结 .............................................................................................................. 65

第六章结论与展望 ...................................................................................................... 67

6.1 结论 ...................................................................................................................... 67

6.2 展望 ...................................................................................................................... 68

参考文献 ........................................................................................................................ 70

附录 ............................................................................................................................ 75

在读期间公开发表的论文和承担科研项目及取得成果 ............................................ 78

致谢 ............................................................................................................................ 79

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