基于FDS的矿井外因火灾数值模拟研究

发布时间：2018-10-20 18:00

【摘要】：矿井外因火灾多发生在风流通畅的地点，火势发展迅速，如果扑救不及时，不仅煤炭资源和矿井设备被烧毁，造成采煤工作面甚至矿井封闭与停产，还可能引起瓦斯、煤尘、水煤汽爆炸或火烟毒化矿井，酿成人员伤亡的重大恶性事故。本文采用实验及数值模拟相结合的方法，对矿井发生外因火灾时烟气的流动特性、温度场、压力场、有毒有害气体浓度等的分布规律作了研究，为矿井发生火灾时救援和人员疏散提供参考。通过巷道火灾小尺寸模型实验对单一水平巷道内发生火灾的情形进行实验研究，记录了火灾时期不同断面不同测点的温度传感器的温度变化情况，并研究了顶棚射流温度的纵向分布规律；通过FDS软件设置同比例模型，以N-S方程为基础，引入浮力修正的k湍流模型、燃烧模型、辐射换热模型，建立了适合描述巷道内烟气流动规律和温度、有毒有害气体浓度分布规律等的计算模型，并优化了网格划分方式，对巷道内火灾进行数值模拟，得到了与实验相吻合的结果。建立了水平巷道数值模拟模型，分别研究了火源热释放速率最大时（120s），CO浓度和温度在不同位置的分布规律，其中沿巷道方向，火源上风向CO浓度随着距离的增大，逐渐减小，且减小的幅度大于下风向，温度的衰减幅度大于CO浓度的衰减幅度；垂直巷道方向上，由于烟气层的影响，CO浓度和温度从上到下均递减；研究了一段下山通风倾斜巷道内发生火灾的情况，对发生风流逆转的情况进行模拟，分析了火源上方及两侧风压和速度的变化情况，并研究了火风压影响因素，火风压随着火源热释放速率的增大而增大，随着角度的增大而增大，其中角度对火风压的影响最大，风速对火风压影响不大；研究了独头平巷中部时发生火灾采取封闭措施时巷道内的各物理参数变化情况，，包括CO浓度，O_2浓度，风压变化，温度变化等，研究表明，火源附近CO最大达0.2%，火区封闭前最大风压为23Pa，封闭火区后风压骤增，最高达650Pa。进行了采煤工作面火灾情况下局部反风的数值模拟实验，对比了火源在进风巷不采取反风措施以及采取反风措施时各巷道的温度场分布、烟气流动、可见度等情况；通过数值模拟，研究了在煤矿井口房火灾情况下，采取全矿井反风措施时竖井内的风压、温度、速度等的变化情况，以及井底车场、巷道内的气体浓度、温度等的分布情况。
[Abstract]:Most of the fires outside the mine occur in places where the air flow is smooth, and the fire develops rapidly. If the fire is not put out in time, not only the coal resources and the mine equipment are burned down, resulting in the coal mining face and even the coal mine being closed and shut down, but also the gas and coal dust may be caused. Coal vapor explosion or smoke poisoning mine, resulting in serious casualties of serious accidents. In this paper, the characteristics of flue gas flow, temperature field, pressure field, concentration of toxic and harmful gases are studied by means of experiments and numerical simulation. To provide reference for mine fire rescue and evacuation. The fire in a single horizontal roadway was experimentally studied by small scale model experiments. The temperature changes of temperature sensors at different measuring points of different sections during the fire period were recorded. The vertical distribution of the roof jet temperature is studied, the model of the same proportion is set up by FDS software, based on the N-S equation, the buoyancy modified k turbulence model, the combustion model and the radiation heat transfer model are introduced. A calculation model suitable for describing the distribution of flue gas flow temperature and concentration of toxic and harmful gases in roadway is established. The mesh division method is optimized and the numerical simulation of the fire in the tunnel is carried out and the results are in good agreement with the experimental results. The numerical simulation model of horizontal roadway is established, and the distribution of the maximum heat release rate (120s), CO concentration and temperature) in different locations is studied respectively. Along the roadway direction, the CO concentration in the wind direction of the fire source decreases with the increase of the distance. The decrease amplitude is larger than the downwind direction, the attenuation amplitude of temperature is larger than that of CO concentration, and the CO concentration and temperature decrease from top to bottom due to the influence of flue gas layer in the vertical roadway direction. This paper studies the situation of fire in a section of downhill ventilation inclined roadway, simulates the situation of wind flow reversal, analyzes the change of wind pressure and velocity above and on both sides of fire source, and studies the influencing factors of fire wind pressure. The fire wind pressure increases with the increase of the heat release rate of the fire source and increases with the increase of the angle, in which the angle has the greatest influence on the fire wind pressure, and the wind speed has little effect on the fire wind pressure. The changes of physical parameters in the roadway, including CO concentration, O _ 2 concentration, wind pressure change, temperature change and so on, are studied when the fire occurs in the middle of the single head roadway. The maximum CO near the fire source was 0.2, the maximum wind pressure was 23 Pabefore the fire area was closed, and the wind pressure suddenly increased after the fire area was closed, the highest was 650 Pa. The numerical simulation experiment of local backwind in coal face fire is carried out, and the temperature field distribution, flue gas flow, visibility and so on of each roadway are compared when the fire source does not take the counter-air measure in the entry air roadway and the counter-air measure is taken. Through numerical simulation, the variation of air pressure, temperature and velocity in the shaft under the condition of coal mine head house fire is studied, and the distribution of gas concentration and temperature in the bottom pit and roadway is also studied.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD752.3

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