不同形状巷道断面风流—瓦斯耦合特性研究

发布时间：2018-02-01 20:48

本文关键词： 风速分布瓦斯浓度分布不同形状巷道风洞模拟实验数值模拟　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：煤矿井下不同断面巷道中,风流流场与瓦斯浓度场相互关联、相互影响,形成了复杂的耦合关系,这种耦合特性直接影响了巷道中瓦斯的分布特征。对于巷道中瓦斯的分布特征掌握的越明确,瓦斯治理措施的实施就越具有精确性,所以,深入研究不同断面巷道中风流-瓦斯耦合特性具有重大的理论意义和实用价值,能够为煤矿通风管理及瓦斯防治提供更为完善的理论指导。本文主要的研究内容是不同形状巷道断面的风速分布规律,瓦斯浓度分布规律以及风流-瓦斯耦合特性,主要研究结论如下:(1)进行半圆拱形巷道断面风速风洞模拟实验,选取洞体内试验段上流场得到充分发展的测量断面上的8条特征线进行非均匀布点风速测量。通过比较不同中心点风速下的边界层低速区厚度,得出风速在0.99~8.46m/s范围内,巷道断面中心点风速对边界层低速区厚度影响不大。在半圆拱风洞模拟巷道中没有障碍物时,风速分布呈现左右基本对称上下差别较大的情形。在以巷道中心为对称点上下对称的位置上,下部的速度明显高于上部。(2)为了掌握不同形状的一般巷道中通风流场和瓦斯浓度场的分布规律,利用最常用的计算流体力学软件Fluent进行数值模拟研究。本文的特色是将巷道两帮的煤壁在模型中做出并用多孔介质模型处理煤壁的瓦斯涌出,然后设定求解控制参数对三种模型的流动域分别进行模拟解算,并利用Tecplot对模拟结果进行后处理。模拟结果显示,三种形状巷道断面风速分布的等值线图的形状分别近似为拱形、矩形和梯形,可见断面上速度的等值线分布曲线与断面形状有关。不同的是拱形巷道的等值线形状是凸起的,而矩形巷道和梯形巷道等值线形状是凹陷的。当风速增大或者瓦斯浓度减小时,等值线的凹陷现象将会减小甚至消失;当风速减小或者瓦斯浓度增大时,等值线的凹陷现象将会更加明显。三种断面上瓦斯浓度分布都比较规律,水平方向上靠近巷道边壁处瓦斯浓度和浓度梯度都是最大的,往巷道中心靠近越来越小;垂直方向上,靠近底板处瓦斯浓度是最小的,往顶板靠近越来越大。(3)对余吾煤矿井下矩形巷道中风速分布进行了数值模拟,将模拟结果与现场实际测定的风速值进行对比分析发现,在巷道的中心区域,同一位置上实测风速值和数值模拟风速值符合的比较好,但是在靠近巷道边壁和管道边壁的区域内同一位置上实测风速值和数值模拟风速值符合的比较差,其中在巷道底板附近数值模拟的风速值几乎一致大于现场实测的风速值,而在巷道顶板附近数值模拟的风速值几乎一致小于现场实测的风速值。
[Abstract]:In different sections of roadway in coal mine, the air-flow field and gas concentration field are interrelated and influence each other, forming a complex coupling relationship. This coupling directly affects the gas distribution characteristics in the roadway. The more specific the gas distribution characteristics in the roadway, the more accurate the gas control measures will be. It is of great theoretical significance and practical value to study the air-flow-gas coupling characteristics in different cross-section roadways. It can provide more perfect theoretical guidance for coal mine ventilation management and gas prevention. The main research content of this paper is the wind velocity distribution law of different shape roadway section. Gas concentration distribution and gas-gas coupling characteristics, the main conclusions are as follows: 1) the wind tunnel simulation experiment of wind speed in semi-circular arch roadway section is carried out. Eight characteristic lines on the measured section with fully developed flow field in the test section are selected to measure the wind speed of the non-uniform distribution of points. The thickness of the boundary layer in the low speed zone is compared under the wind speed at different central points. The results show that in the range of 0.99 ~ 8.46 m / s, the wind speed at the center of the tunnel section has little effect on the thickness of the boundary layer in the low speed zone, when there are no obstacles in the semi-circular arch wind tunnel simulation roadway. The distribution of wind speed shows a big difference between the left and right basic symmetry, and the center of the roadway is the symmetrical position of the top and bottom of the symmetrical point. The velocity of the lower part is obviously higher than that of the upper part.) in order to master the distribution law of the air flow field and the gas concentration field in the general roadway with different shapes. The most commonly used computational fluid dynamics software Fluent is used to carry out numerical simulation research. The characteristic of this paper is that the coal wall of two sides of roadway is made in the model and the porous medium model is used to deal with the gas emission from coal wall. Then set up the control parameters to solve the flow field of the three models, respectively, and use Tecplot to post-process the simulation results. The simulation results show. The contour map of wind velocity distribution in three kinds of roadway sections is approximately arched rectangular and trapezoidal respectively. The contour distribution curve of velocity on the section is related to the shape of the section. The difference is that the contour shape of the arch roadway is raised. The contour shape of rectangular roadway and trapezoidal roadway is concave. When the wind speed increases or the gas concentration decreases, the concave phenomenon of isoline will decrease or even disappear. When the wind speed decreases or the gas concentration increases, the concave phenomenon of the isoline will be more obvious. The distribution of gas concentration on the three sections is more regular. In the horizontal direction, the gas concentration and concentration gradient near the side wall of the roadway is the largest, and the gas concentration gradient is getting smaller and smaller to the center of the laneway. In the vertical direction, the gas concentration near the floor is the smallest, and the wind velocity distribution in the underground rectangular roadway of Yuwu coal mine is numerically simulated. By comparing the simulation results with the field measured wind speed values, it is found that the measured wind speed values and the numerical simulation wind speed values are in good agreement in the center area of the roadway. However, in the same position near the side wall of roadway and the side wall of pipeline, the comparison between the measured wind velocity value and the numerical simulation wind velocity value is very bad. The numerical simulation wind speed near the roadway floor is almost consistent with the field measured wind speed value, while the numerical simulation wind speed value near the roadway roof is almost consistent with the field measured wind speed value.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712;TD721

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