天然气管道泄漏与天然气在大气中扩散的模拟研究(fluent模拟)

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哈尔滨工业大学工学硕士学位论文
Abstract
With the development of na tural gas pi peline i ndustry, more a nd m ore people tend t o us e na tural gas. D uring t he na tural ga s g athering a nd t ransportation pr ocess, leakage m ay oc cur f or strictness s eal, erosion and artificial ma ladministration. After natural gas di ffusing into the a tmosphere, mixing w ith air a nd forming inf lammable premix gasses, it is likely to initiate fire or explosion if meet ignition sourees; Even if the fire or explosion doesn’t occur, the leaking natura gas and its concomitant will still stay at atmosphere, this will have a bad effect on human health and environment for a long time in the future. S o that the leakage of natural gas will not only result in the lost of energy source material, c ause huge economic l oss, but also cause malignancy accident, such as fire, explosion, p oisoning, and so o n. Therefore, to carry out numerical simulation study on natural gas pipeline leakage，diffusion and explosion will mean a lot to transportation security and life and property safety. This paper bases on hydromechanics, thermodynamics, computational mathematics and computer technology, researehes on the methods of the diffusion instance after natural gas leakage，analyses rules of diffusion. Firstly, this paper analyses the research status of gas leakage, diffusion in domestic and abroad, studies the jet theory, deduces the basic equation of gas flowing. Secondly, establishing a m athematical model of the leakage rate and using MATLAB to prepare procedures for calculating the leakage rate. Thirdly, bases on the hydromechanics and thermodynamics elementary theory, this paper establishes a mathematical model of natural gas diffusion after leaking into atmosphere, applies finite element method to solve the partial differential equation group in the model. Ultimately, bases on above-mentioned m odels, adopts c omputational f luid m echanics simulation software- FLUENT to simulate the na tural ga s leakage a nd di ffusion, and analyses di ffusion i mpacted b y di fferent w ind s peed, pr essure, l eakage a perture a nd impediments. The r esearch r esults of na tural ga s l eakage a nd diffusion num erical s imulation in this paper coincides with the leakage and diffusion theory very well. Thereby the correctness of theoretical analysis in this paper is proved. The research method provides a new clue for the natural gas leakage and diffusion theoretical research. The discipline gained from analysis has certain guidance significances and reference value for the natural gas line’s transportation safety and maintenance. Keywords: natural gas, pipeline, leakage, diffusion, numerical simulation
Classified Index：TU996.6 U.D.C：696
Dissertation for the Master Degree in Engineering
RESEARCH ON NATURAL GAS LEAKAGE AND DIFFUSION NUMERICAL SIMULATION
国内图书分类号：TU996.6 国际图书分类号：696
学校代码：10213 密级：公开
工学硕士学位论文
天然气管道泄漏与天然气在大气中 扩散的模拟研究
硕 士 研究生：侯庆民 导 师：焦文玲 教授 申 请 学 位：工学硕士 学 科、专 业：供热、供燃气、通风及空调工程 所 在 单 位：市政环境工程学院 答 辩 日 期：2009 年 6 月 授予学位单位：哈尔滨工业大学
Candidate: Supervisor: Academic Degree Applied for: Speciality: Affiliation： Date of Defence: Degree-Conferring-Institution:
Hou qingmin Prof. Jiao Wenling Master of Engineering Heating，Gas Supplying，Ventilating & Air conditioning Engineering School of M unicipal a nd E nvironmental Engineering June，2009 Harbin Institute of Technology
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哈尔滨工业大学工学硕士学位论文
目
摘
录
要 ...................................................................................................................... I
Abstract ........................................................................................................................ II 第 1 章 绪论 ................................................................................................................ 6 1.1 课题的背景与意义............................................................................................ 6 1. 2 国内外研究现状 ................................................................................................ 8 1.2.1 国外现状 ...................................................................................................... 8 1.2.1 国内现状 ...................................................................................................... 9 1.3 本文的研究工作 ........................................................................................... 11 第 2 章 天然气泄漏扩散的机理研究 ...................................................................... 12 2.1 射流理论概述 ................................................................................................... 12 2.1.1 射流的分类 ................................................................................................ 12 2.1.2 均匀环境的浮力射流 ................................................................................ 13 2.1.3 天然气管道泄漏的射流特点 .................................................................... 14 2.2 气体流动基本控制方程 ................................................................................... 15 2.2.1 连续性方程 ................................................................................................ 15 2.2.2 运动方程 .................................................................................................... 15 2.2.3 能量方程 .................................................................................................... 16 2.2.4 本构方程 .................................................................................................... 16 2.2.5 状态方程 .................................................................................................... 16 2.3 本章小结........................................................................................................... 17 第 3 章 天然气管道泄漏率模型的建立 .................................................................. 18 3.1 小孔泄漏率模型的推导 ................................................................................... 18 3.2 管道（全截面破裂）泄漏率模型的推导 ....................................................... 21 3.3 大孔泄漏率模型的推导 ................................................................................... 22 3.4 用MATLAB编写计算程序 .............................................................................. 24 3.5 本章小结 ........................................................................................................... 24 第 4 章 天然气扩散的模拟研究 ............................................................................ 25 4.1 天然气扩散模型的建立................................................................................... 25 4.1.1 空气流动方程 ............................................................................................ 25 4.1.2 对流扩散方程 ............................................................................................ 25
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哈尔滨工业大学工学硕士学位论文
摘
要
随着天然气管道工业的发展，天然气用户越来越多。天然气在集输过程中，由 于管道系统连接件之间的密封不严、腐蚀穿孔、人为管理不善等因素会引起天然气 泄漏。天然气泄漏后扩散到大气中，与空气混合形成可燃预混气体，遇见点火源， 可能会引发火灾或者爆炸；即使不发生着火爆炸，泄漏出的天然气及其伴生物滞留 在大气中，在未来较长时期对人类健康和生态环境会造成不良影响。所以，天然气 泄漏不仅会导致能源物料流失，造成巨大的经济损失，还会引起火灾、爆炸、中毒、 伤亡等恶性事故，严重威胁着人民生命财产的安全。因此，进行天然气管道泄漏扩 散及爆炸数值模拟研究，对管道输送安全运营和保障人生财产安全意义重大。 本文基于流体力学、热力学、计算数学和计算机技术，对天然气管道发生泄漏 后的扩散情况进行方法研究和规律分析。首先，分析了国内外在气体泄漏和扩散方 面的研究现状，对射流理论进行分析，研究了气体流动的基本控制方程；其次，建 立了天然气管道泄漏率模型并利用 MATLAB 编写了计算泄漏率的程序；再次，根 据流体力学和热力学基本理论，建立了天然气泄漏后在大气中扩散数学模型，应用 有限元方法对模型的偏微分方程组进行离散求解；最后，基于上述模型，采用计算 流体力学仿真软件 FLUENT 对天然气泄漏扩散进行模拟计算，并分析风速、压力、 泄漏孔径以及障碍物的变化对扩散结果的影响。 本文的天然气泄漏以及扩散的数值模拟研究结果与泄漏、扩散理论相符，从而 验证了本文理论分析的正确性，所提出的研究方法为天然气泄漏扩散研究提供了一 种分析思路，分析所得到的规律对天然气管道的安全运营和维护有一定的指导意义 和参考价值。 关键词：天然气；管道；泄漏；扩散；数值模拟