受限空间内气体扩散的数值模拟及分析.doc

大连理工大学硕士学位论文受限空间内气体扩散的数值模拟及分析姓名：王治华申请学位级别：硕士专业：安全技术及工程指导教师：李岳20090601大连理工大学硕士学位论文摘 要化工生产中大量生产和使用易燃、易爆和有毒等危险性气体，过去发生的意外泄漏 事故给社会带来了严重的灾害，也给人们留下了深刻的教训，1970年美国矿务局公布了 “海上运输时液化天然气泄漏的危害”的研究报告，这触发了国际上对危险气体扩散问 题的研究，而且扩散模式数学模拟的研究成为了迅速发展且先进的研究领域近年来， 随着计算机技犬的迅速发展，人们把先进的计算机技术运用到数值模拟领域，开发出了 各种优秀的数值模拟软件，其中FLUENT软件就是现在在流动和传热领域被人们广泛 应用的数值计算软件本文针对受限空间中可燃性气体的意外释放，运用FLUENT软 件对其输运和扩散过程进行了数值模拟，得到可燃性气体浓度的时空分布，并分析了不 同影响因素对可燃性气体扩散的影响，这对火灾报警等事故预防、事故发生后制定应急 措施以及安全评价都有着重要的指导意义本文的主要内容及结论如下：(1) 利用CFD方法建立了受限空间内气体扩散的数学模型，结合FLUENT软件阐 述了气体扩散的数值模拟所用到的数值方法，其中对空间内空气的湍流采用RNGk- e湍 流模型，运用组分输运模型对扩散过程进行模拟及SIMPLE算法来对流场进行数值计 算；(2) 在前述的数学模型基础上利用FLUENT软件对通风房间内氢气的扩散过程进行 了数值模拟，把数值计算的结果和相关文献中的实验数据进行对比，确定了前面所建立 数学模型的正确性，及运用ELUENT软件对气体扩散数值模拟的准确性和可行性；(3) 根据前面数值计算的结果讨论了通风房间内氢气浓度分布的特点，给出了浓度 分布的形象图形显示，并研究了通风口位置的改变和有障碍物存在时对气体扩散的浓度 场和速度场影响；(4) 建立了简化的煤矿坑道内甲烷气体泄漏扩散的物理模型和数学模型，模型中加 入外界通风速度的影响，着重讨论有障碍物存在时坑道内的甲烷浓度分布特点，并对坑 道内气体的泄漏速率、障碍物尺寸(高度、宽度)、泄漏源至障碍物的距离、泄漏源与 障碍物的相对位置、气体密度等因素对坑道内气体扩散和浓度分布的影响分别进行了深 入研究，给出了相关结论，并以得到的结论为基础，对煤矿坑道内可燃气体报警器的安 装位置提供了可借鉴的指导意义。

关键词：受限空间；扩散；数值模拟；浓度分布受限空间内气体扩散的数值模拟及分析The Numerical Study On Diffusion Of Gases In Limited SpaceAbstractThe accidental release of vast flammable, explosive or toxic materials produced and used in modem industries would bring about a great disaster to the society and what happened has left a deep lesson to the person. Since 1970 the United States Bureau of Mines published the report of "hazardous of LNG Spillage on Marine Transportation^, which mad international researchers to pay attention to the study of diffusion and then the numerical simulation of diffusion of gases become the rapid development and advanced research field. Recently with the rapid development of computer technology, a variety of excellent numerical simulation code was developed in numerical calculation field including FLUENT which has been widely used in the field of fluid flow and heat transfer. The thesis simulated the transportation and diffusion of gases accidentally released in limited space with FLUENT code and showed the concentration contour maps of gases with time and space and the velocity vector distribution, and then studied deep into the influence of different influencing factors to the diffusion of gases and gave the related conclusions. It has a big significance both in accident prevention such as fire alarm and the development of emergency rescue measures after it happened and in safety assessment・ The main work and conclusions in this paper are as follows:1) A mathematical model was created to simulate the diffusion of gases in limited space and illustrate the numerical methods being used, the RNG k- e turbulence model was used to describe the txirbulence of air in the space and species transport model was activated and SIMPLE algorithm was utilized to calculate the flow of the fluid.2) Based on the mathematical model of gases in limited space, the transportation and difliision of hydrogen was simulated using the FLUENT code and the calculated results was compared with the experimental data in related reference and it was proved that the mathematical model of diffusion of hydrogen in the ventilated room is right and the algorithm with the FLUENT code being chose is accurate and feasible・3) According to the calculated results of the hydrogen diffusion in the ventilated room, the characteristics of concentration distribution of hydrogen is discussed and study deep into the influence of change of location of vent and the existence of barrier to the concentration distribution of hydrogen and velocity vector distribution.Based on the precedent numerical simulation example, the diffusion model of methane in the simplified cual mine tunnel was created and added the consideration of wind-II -velocity outside. The concentration distribution of methane in the simplified coal mine tunnel with the barrier existed was discussed and study deep into the concentration contour maps and velocity vector distribution on different conditions such as:the different velocity of release ,thc different size of barricr(width and height of barrier), the unequal distance between the leakage source and the barrier, the relative location between leakage source and the barrier and the different density of the gases. And then the related conclusion was given and based on that some suggestion was given to the fixing of the combustible gas alarm・Key Words： Combustible Gas; Diffusion; Numerical Study; Concentration Distribution-in-大连理工大学学位论文独创性声明作者郑重声明：所呈交的学位论文，是本人在导师的指导下进行 研究工作所取得的成果.尽我所知，除文中已经注明引用内容和致谢 的地方外，本论文不包含其他个人或集体已经发表的研究成果，也不 包含其他已申请学位或其他用途使用过的成果。

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