无约束云团爆炸流动耦合规律研究

发布时间：2018-03-21 08:25

本文选题：云团爆炸　切入点：内置结构　出处：《北京理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：可燃气云爆炸是工业生产和生活领域爆炸灾害的主要形式之一,内置结构在云团爆炸中的作用非常复杂,气体在爆炸过程中的流动性更增加了气云爆炸的复杂性,科学的认识可燃气云爆炸及其流动性耦合规律是有效预防和控制爆炸事故亟待解决的关键课题。本文以甲烷/空气、丙烷/空气、氢气/空气云团为研究对象,运用数值计算对无约束云团爆炸及其流动耦合规律展开研究,探索了云团内置结构、浓度、体积及气体活性对爆炸物理特征的影响规律,主要工作和创新性成果如下:一、内置结构对云团爆炸特性的影响规律揭示了内置结构影响气云爆炸过程的双重特征,内置结构阻塞比及其空间分布对气云爆炸参数具有同样重要作用。在内置结构的空间分布一定时,气云爆炸参数在某一阻塞比下取得最大值;在障碍物阻塞比一定时,内置障碍物越稠密,气云爆炸参数越大。在本文计算条件下,障碍物空间分布为8 x 8 x 4时,甲烷/空气云团爆炸参数在阻塞比为0.74时取得最大值;障碍物阻塞比为3.07时,甲烷/空气云团爆炸参数随着障碍物排列变得稠密,爆炸参数逐渐增大。研究发现,动压量级可达104 Pa,同样具有强大的破坏作用,另外燃烧区大于初始预混区,燃烧区大小主要受障碍物阻塞比影响,阻塞比越大,燃烧区越小。二、云团爆炸冲击波与高温流动的耦合规律揭示了气云爆炸冲击波和高温流动在时间和空间上的耦合规律,内置结构的空间分布一定时,随着阻塞比增大,两者峰值间的时差间隔先减小后增大,在某一阻塞比下取得最小值;阻塞比一定时,障碍物排列越稠密,两者峰值间的时差间隔越小。在本文计算条件下,障碍物空间分布为8 x 8 x 4时,两者峰值间的时差间隔随着阻塞比增大先减小后增大,在阻塞比为0.74时取得最小值;障碍物阻塞比为3.07时,随着障碍物排列变得稠密,两者间时差间隔逐渐减小。三、不同浓度云团爆炸的物理特性本文对贫燃料和富燃料浓度甲烷/空气云团爆炸进行数值模拟,发现不同浓度甲烷/空气云团爆炸超压的衰减趋势不完全相同,富燃料浓度云团爆炸超压在一定条件下会出现压力突升,贫燃料浓度时,当障碍物密度足够大时在障碍物区边界处会出现压力上升。不同浓度的燃烧率衰减趋势也不完全相同,化学计量浓度和7%贫燃料浓度的燃烧率随着距离变化单调递减,而12%富燃料浓度时在衰减阶段再次出现燃烧率增大。四、云团爆炸的体积效应及规律揭示了云团爆炸特性的体积效应,温度场分布体积效应显著,化学计量浓度和贫燃料浓度时,云团体积越大,无量纲稳定高温区域越大;富燃料浓度时,云团体积越大,无量纲稳定高温区域越小。火焰区分布同样具有明显体积效应,化学计量浓度时,无量纲火焰区域随云团体积增大逐渐增大,7%贫燃料时不同体积云团爆炸的无量纲火焰区域基本相同,12%富燃料浓度时无量纲火焰区域随云团体积增大逐渐减小。气云爆炸效应的几何相似不再成立,爆炸参数与无量纲距离的关系与云团的体积相关,随着云团体积增大,相同无量纲距离处的爆炸超压、动压和燃烧率均增大,而温度场分布略有不同,贫燃料和化学计量浓度的爆炸温度随着云团体积增大逐渐增大,富燃料浓度时爆炸温度随云团体积增大逐渐减小。
[Abstract]:Flammable gas explosion is one of the main forms of the field of industrial production and life explosion disasters, in structure in the cloud explosion in very complex, liquidity in the process of explosion gas increases the complexity of gas explosion, scientific understanding of flammable gas explosion and its flow coupling rule is a key issue for effective prevention and the explosion control needs to be solved. In this paper, methane / air, propane / air and hydrogen / air cloud as the research object, the calculation of unconstrained cloud explosion and its flow is studied by numerical coupling law, explore the cloud internal structure, concentration, influence of volume and gas explosion on the activity of physical characteristics, the main work and the innovative results are as follows: first, effect of internal structure on cloud explosion characteristics reveals the dual characteristics of internal structure affect the explosion process of gas cloud, built-in structure and blocking The spatial distribution of explosion parameters also play an important role on the gas cloud. In the spatial distribution of a built-in structure, gas cloud explosion parameters in a blocking ratio reached the maximum value; in the blockage ratio, built-in obstacles more dense gas cloud explosion parameter is large. In this paper calculation conditions, obstacles the spatial distribution of 8 x 8 x 4, methane / air cloud explosion parameters in the blocking ratio of 0.74 has a maximum value; the blockage ratio is 3.07, the methane / air cloud explosion parameters with obstacle arrangement becomes dense, the explosion parameter increases. The study found that the dynamic pressure magnitude can reach 104 Pa also has strong destructive effect, in addition to the combustion zone is greater than the initial pre mixing zone, combustion zone is mainly controlled by the blockage ratio, blocking ratio is larger, the smaller area of combustion. Two, cloud explosion shock wave and high temperature flow coupling law reveals the gas cloud The coupled flow law of explosion shock wave and high temperature in time and space, the space distribution of a built-in structure, with the blocking ratio increases, the peak time interval between the first decreases and then increases at a blockage ratios has a minimum value; blocking ratio, obstacle arrangement more dense, time interval between the two the peak between the smaller calculation conditions. In this paper, the obstacle space distribution of 8 x 8 x 4, two peak between the time interval with the blocking ratio first decreases and then increases, the blocking ratio of 0.74 is the minimum; the blockage ratio is 3.07, the obstacles are become dense between the time interval decreased gradually. Three, the physical properties of different concentrations of cloud explosion fuel lean and rich fuel concentration of methane / air cloud explosion numerical simulation, found that the attenuation trend of different concentrations of methane / air cloud explosion overpressure Not exactly the same, the fuel rich concentration of cloud explosion overpressure in certain conditions will appear under the pressure rise, lean fuel concentration, when the obstacle density is large enough in the boundary obstacles occur at different concentrations. The combustion pressure rise rate attenuation trend is not exactly the same, the stoichiometric concentration and 7% lean fuel concentration the burning rate with decreasing distance changes and monotonous, 12% fuel rich concentration in the decay phase again burning rate increases. Four, volume effect and regularity of cloud explosion reveals the volume effect of cloud explosion characteristics, temperature field distribution volume effect significantly, concentration of stoichiometric concentration and poor fuel, the cloud volume is large, no the dimensional stability of high temperature area is larger; the fuel rich concentration, the cloud volume is large, the dimensionless stability in high temperature region. The smaller the flame zone distribution also has obvious volume effect, the stoichiometric concentration, the dimensionless fire The flame area gradually increases with the increase of the cloud volume, the dimensionless flame region 7% lean fuel when the different volume of cloud explosion is basically the same, 12% dimensionless concentration of fuel rich flame region with the cloud volume decreases with increasing of gas cloud explosion effect. The geometric similarity is no longer valid, the explosion parameters and the dimensionless distance relationship with the cloud volume related with the cloud volume increases, the same dimensionless distance of explosion overpressure, dynamic pressure and combustion rate are increased, the temperature distribution is slightly different, the fuel lean and stoichiometric concentration with increasing volume of cloud explosion temperature gradually increased, when the concentration of the fuel rich explosion temperature with cloud volume increases gradually decreases.

【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X932

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