园区大气污染物分布预测数值模拟研究

论文总字数：30014字

摘 要

随着城市化趋势的加速，人们越来越关注城市的大气环境。环保意识缺乏、能源利用率不高、资金投入不足等导致了一系列环境问题。例如，城市大气中悬浮颗粒物含量普遍超标、机动车尾气排放量快速增长造成严重的NOx、二氧化硫污染。这些都极大地威胁到了居民的身体健康。本文基于微气象学和计算流体力学（CFD），对园区内风场和NOx分布进行研究，有利于加强对园区级污染物扩散规律的认识。

本文针对一个给定的园区，重构该园区的三维结构及周边环境并划分网格，基于大涡模拟（Large Eddy Simulation, LES）开展园区内气相输运的CFD数值模拟，获得在不同风向、风力条件下园区内风场数据。以路源NOx为主要污染物，开展气态污染物输运数值模拟，获得园区内污染物分布特性。分析风向、风力对园区内污染物分布的影响。

主要结论为：不同风向的园区内部气风场存在显著差异。园区的几何结构及两侧建筑物高度对园区的风场及污染物浓度场特征有很大的影响。在本文选取的7m/s的速度条件下，近地面风场受建筑物布局影响差别很大，40m处高楼风成为风场的主要影响因素。园区内部形成明显的空气漩涡，污染物质量浓度分布出现背风面高于迎风面的典型环流规律。 在空间上，垂直剖面上污染物质量浓度的垂直分布具有明显的分层特征。

本文仅针对园区外的路源污染物进行了初步探讨分析，真实园区特别是含有污染源的园区内的污染物分布和预测仍需进一步探索研究。

关键词：大涡模拟、风场、污染物扩散

Abstract

With the acceleration of urbanization, people are paying more and more attention to the atmospheric environment of the cities. Lacking of awareness of environmental protection, low energy utilization rate and insufficient financial investment have led to a series of environmental problems, e.g., widely standard exceeding suspended particulate matter, NOx and SO₂ pollution caused by the rapid increase of vehicle exhaust These pollutants have greatly threatened the health of the residents. Based on micrometeorology and computational fluid dynamics (CFD), this paper studies the wind field and NOx distribution in an industrial park. It is helpful to strengthen the understanding of the diffusion mechanisms of pollutants at the industrial park level.

For a given industrial park, the three-dimensional structure of the park and the surrounding environment were reconstructed. Mesh for simulation was divided accordingly. Numerical simulation of gas phase transport in the park was carried out based on large eddy simulation (LES), and flow field data were obtained under different wind direction and velocity conditions. Taking surrounding highways’ NOx as the main pollutant source, numerical simulation of gaseous transport was carried out to obtain the pollutant distribution characteristics in the industrial park. The effects of the wind direction and velocity on the pollutant distribution were analyzed.

The main conclusions could be drawn. Wind direction has significant influence on the park’s wind field. The geometric structure of the park and the height of buildings on both sides have great influence on the flow field and pollutant distribution of the park. The near-surface wind field is affected by the layout of buildings, and the wind from 40m tall buildings becomes the main influencing factor of the wind field when the wind speed is 7 m/s. An obvious air vortex is formed inside the park. The mass concentration of pollutants presents a typical circulation that the leeward side is higher than the windward side. The vertical distribution of pollutant mass concentration on the vertical section has obvious stratification characteristics.

This paper only makes a preliminary discussion of the road source pollutants outside the park. The distribution and prediction of pollutants in real industrial parks, especially those containing pollution sources still need further exploration.

KEY WORDS: Large eddy simulation，wind field，pollution diffusion

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 研究背景及意义 1

1.2国内外研究进展 1

1.3研究思路和模拟过程 4

1.4本章小结 5

第二章 控制方程 6

2.1大涡模拟控制方程 6

2.2气态污染物扩散模型方程 7

2.3本章小结 7

第三章 模拟对象与条件 8

3.1园区物理模型 8

3.2 数值模拟设置 12

3.3本章小结 12

第四章 风场分析 13

4.1不同风向对风场的影响 13

4.1.1不同风向对0.5m高度风场的影响 13

4.1.2不同风向对5m高度风场的影响 14

4.1.3不同风向对40m高度风场的影响 14

4.1.4不同风向对170m高度风场的影响 15

4.1.5不同风向对平行风向截面园区风场的影响 16

4.1.6不同风向对垂直风向截面园区风场的影响 18

4.2不同风力对风场的影响 20

4.2.1不同风力对园区0.5m高度风场的影响 20

4.2.2不同风力对园区5m高度风场的影响 21

4.2.3不同风力对园区40m高度风场的影响 22

4.2.4不同风力对园区170m风场的影响 22

4.2.5不同风力对园区平行风向风场的影响 23

4.2.6不同风力对园区垂直风向风场的影响 24

4.3本章小结 26

第五章 污染物场分析 27

5.1不同风向对污染物的影响 27

5.1.1不同风向对0.5m高度污染物场的影响 27

5.1.2不同风向对5m高度污染物场的影响 28

5.1.3不同风向对40m高度污染物场的影响 28

5.1.4不同风向对170m高度污染物场的影响 29

5.1.5不同风向对平行风向截面园区污染物场的影响 30

5.1.6不同风向对水平风向截面园区污染物场的影响 32

5.2不同风力对污染物场的影响 33

5.2.1不同风力对园区0.5m污染物场的影响 33

5.2.2不同风力对园区5m污染物场的影响 34

5.2.3不同风力对园区40m污染物场的影响 35

5.2.4不同风力对园区170m污染物场的影响 36

5.2.5不同风力对园区平行风向污染物场的影响 37

5.2.6不同风力对园区垂直风向污染物场的影响 38

5.3 本章小结 40

第六章 结论与展望 41

参考文献： 42

致 谢 45

第一章 绪论

1.1 研究背景及意义

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