多相光催化反应器的数值模拟
VIP免费
摘 要
由两侧都是连续高大建筑物组成的相对狭长街道称为街道峡谷，是城市的基
本组成部分。机动车排放所形成的交通污染已成为国内外大都市中空气污染的最
主要来源。且机动车尾气中存在大量对人体有毒害作用的气体。街道峡谷内污染
物对流扩散已成为当前环境领域的研究热点。而在城市中，大气污染物的扩散主
要受到风、大气湍流、温度层结、大气稳定度以及地面建筑物布局等的影响，因
为风等自然因素是不可控的，因此通过改变建筑物的结构形状及建筑布局来控制
城市交通污染物的对流扩散有着比较实际的意义。本文数值模拟了不同建筑物构
型（考虑了台阶结构、廊道结构以及峡谷的非对称性）下，城市街道峡谷内的气
流运动和污染物扩散。并对几种特定工况的城市街道峡谷及孤立街道峡谷做了风
洞实验，将数值模拟结果与风洞实验结果作对比分析，验证数值模拟的可行性，
并比较分析城市街道峡谷与孤立街道峡谷的风洞实验结果。
基于二维不可压缩流动的 N-S 方程、标准 k-
湍流模型和污染物对流扩散方
程，构建模拟城市街道峡谷内气流运动和污染物扩散的 CFD（计算流体动力学）
模型。采用与德国汉堡大学风洞试验验证过的 CFD 模型，在 FLUENT 平台上，对
48 种不同建筑物结构及布局的城市街道峡谷，模拟计算了来流风速为 5m/s 时峡谷
内的气流运动及污染物扩散，结果表明城市街道峡谷内气流旋涡结构和污染物分
布与建筑物结构密切相关：
台阶形建筑结构对城市街道峡谷内气流运动及污染物扩散影响显著。当背风
建筑物含台阶且台阶总降幅较大时，街谷内旋涡结构会发生改变，旋涡也会一定
程度上发生变形。比如工况二、工况四十一和工况四十六，街谷上部为旋涡中心
偏右的顺时针旋涡，街谷下部产生了一个逆时针旋涡，且上部顺时针旋涡的强度
大于下部逆时针旋涡的强度，在逆时针旋涡的作用下街谷内的污染物朝迎风侧下
部迁移，而工况六、工况十九、工况三十一和工况三十六，街谷内旋涡均发生了
不同程度的变形。当迎风建筑物带台阶且台阶总降幅较大，背风建筑物含台阶或
廊道结构，街谷内迎风面、背风面及近地面污染物浓度值均低于平顶工况，此类
街谷布局形态有利于街谷内污染物扩散。
背风建筑物的廊道结构及廊道高度对街谷内流场影响不大，街谷内均生成一
个大的顺时针旋涡，旋涡中心位于街谷中心附近位置，且当背风建筑物的廊道高
度较高时，廊道内均形成逆时针小旋涡，导致背风建筑物廊道内污染物浓度升高，
但当背风建筑物的廊道高度不高时，廊道内均无明显气流现象。而迎风建筑物的
廊道结构及廊道高度对街谷内流场会产生影响，街谷内旋涡均发生了不同程度的
变形。
根据数值模拟工况的建筑物形状结构尺寸，采用 1:500 的模型比尺和在 5m/s
的来流风速下，通过风洞实验研究了 6种不同建筑物结构下的城市街道峡谷及 6
种孤立街道峡谷内污染物对流扩散。结果表明：城市街道峡谷内主要生成顺时针
旋涡，使得污染物朝背风侧聚集。而孤立街道峡谷内主要生成逆时针旋涡，街谷
内迎风侧污染物浓度高于背风侧。且以上几个城市街谷工况的数值模拟结果与风
洞实验结果吻合的较好，验证了数值模型的可行性。
关键词：建筑物结构 城市街道峡谷 CFD 数值模拟 风洞实验
ABSTRACT
A typical configuration is the so-called street canyon, 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, and further increase of traffic is
expected, investigations of dispersion processes in street canyons have become a focal
point in environment research. The dispersion of atmospheric pollutants in urban
environments depends on the turbulent airflow around complex building structures. In
this study, the airflow and pollutant dispersion inside street canyons formed by various
building configurations (the step-like shape, galleries and asymmetrical structures are
considered) were investigated through both numerical simulation and wind-tunnel
experiment.
A two-dimensional computationalfluid dynamics (CFD) model for evaluating the
airflow and pollutant dispersion within astreet canyon wasbuilt up, which was based on
the incompressible N-S equations, standard k-
turbulence model and the pollutant
transportation equation. The airflow and pollutant dispersion within 48 kinds of street
canyons were simulated by using the FLUENT code under an inflow velocity of 5m/s.
The simulation results indicate that the airflow vortex structure and pollutant
distribution are highly relatedto the building structures:
The step-shaped structure building is one of the significant factors that effect the
airflow and pollutant dispersion inside street canyons. When lee building with stairs and
stairs total drop is large, the vortex structure change within street canyon, vortices can
also be to some extent distorted. When the windward building with stairs and stairs
always fall in the big, leeward building structure with stairs or corridor, valley in the
windward, leeward side of the street and near-ground concentrations of pollutants are
lower than the flat-top condition, so such street canyons layout conducive to diffusion.
Leeward buildings of corridor structure and the corridor height on street valley has
little effect on the airflow, street valley are generated a big of clockwise vortex, and
vortex center is located in street valley center, and when leeward buildings of corridor
height high, corridor within are formed counterclockwise small vortex, led to leeward
buildings corridor within pollutants concentration increased, but when leeward
buildings of corridor height not high, corridor within are no obviously airflow
phenomenon. Wind corridor structure and the corridors of the building height on flow
field within street canyon will have an impact, vortex takes place within street canyon
with varying degrees of deformation.
Under the inflow velocity of 5m/s, the pollutant dispersion inside 12 kinds of street
canyons (including 6 urban street canyon cases and 6 isolated street canyon cases)
formed by different shapes through wind-tunnel experiment using a model scale of
1:500. The results show that: In the urban environment, a large counter-clockwise
vortex is formed and makes the pollutant move to the leeward side; while passing across
the isolated street, the airflow is separated abruptly, which leads to the formulation of a
large clockwise vortex on the canyon and brushes the pollutants onto the windward side.
By comparing the wind-tunnel experiments with the simulated dates, the calculated
results agree reasonablely well with the tunnel experiment.
Key Word: Building structure, Urban street canyon, CFD,
Wind-tunnel experiment
目 录
中文摘要
ABSTRACT
第一章 绪 论 ........................................................ 1
1.1 课题研究背景及意义 ............................................. 1
1.2 街道峡谷简介及研究现状 ......................................... 2
1.2.1 街道峡谷简介 ............................................... 2
1.2.2 街道峡谷内污染物扩散的研究方法及研究现状 ................... 3
1.3 课题的提出及意义 ............................................... 6
1.4 课题研究内容及方法步骤 ......................................... 7
1.5 本章小结 ....................................................... 8
第二章 城市街道峡谷内污染物扩散的数值模拟理论基础及数值模型建立 .... 10
2.1 计算所采用的城市街道峡谷结构尺寸 .............................. 10
2.2 计算流体动力学理论基础 ........................................ 13
2.2.1 气流运动控制方程 .......................................... 14
2.2.2 污染物对流扩散方程 ........................................ 18
2.2.3 计算域和边界条件 .......................................... 19
2.2.4 网格划分 .................................................. 20
2.2.5 数值算法 .................................................. 21
2.3 本章小结 ...................................................... 21
第三章 城市街道峡谷数值模型验证与分析 .............................. 22
3.1 德国汉堡大学风洞实验介绍 ...................................... 22
3.2 模型验证与分析 ................................................ 24
3.3 本章小结 ...................................................... 25
第四章 不同建筑物结构下城市街道峡谷内气流运动及污染物扩散的数值模拟分
析 ................................................................. 26
4.1 不同建筑物结构形态下城市街道峡谷内流场数值分析 ................ 26
4.2 不同建筑物结构形态下城市街道峡谷内污染物扩散的数值模拟结果分析 42
4.2.1 城市街道峡谷内迎风面及背风面污染物分析 .................... 43
4.2.2 城市街道峡谷内近地面污染物扩散模拟分析 .................... 48
4.3 本章小结 ...................................................... 55
第五章 不同建筑物结构下城市街道峡谷内污染物对流扩散风洞实验 ........ 56
5.1 上海理工大学环境风洞概况 ...................................... 56
5.2 风洞实验设备、实验模型与测量方法 .............................. 59
5.2.1 实验设备 .................................................. 59
5.2.2 实验模型 .................................................. 59
5.2.3 测量方法 .................................................. 63
5.3 风洞实验 ...................................................... 63
5.3.1 实验原理 .................................................. 63
5.3.2 实验步骤 .................................................. 64
5.3.3 实验结果及其分析 .......................................... 65
5.4 本章小结 ...................................................... 78
第六章 结论及展望 .................................................. 79
6.1 结论 .......................................................... 79
6.2 展望 .......................................................... 80
参考文献 ........................................................... 81
附 录 .............................................................. 86
在读期间公开发表的论文和承担科研项目及取得成果 ..................... 88
致 谢 .............................................................. 89
相关推荐
作者：侯斌
分类：高等教育资料
价格：15积分
属性：93 页
大小：8.15MB
格式：PDF
时间：2025-01-09
