开敞空间可燃气云爆炸数值模拟研究
发布时间：2018-08-30 11:27
【摘要】：随着现代化工生产企业的快速发展,因可燃气体泄漏导致的重大安全生产事故频繁发生,可燃气体的爆炸往往会直接致使重大的伤亡事故和财产损失,其中重要的原因之一就是对可燃气体发生爆炸的机理和规律的研究不够充分,导致在突发事件发生后,防爆和抑爆装置未能起到很好的效果。目前为止,许多学者针对可燃气体的爆炸已经展开了比较深入的研究和探索,然而由于其爆炸的危险性和复杂性,对其不同条件下发生爆炸的规律研究仍然是该领域研究的热点和难点。计算机的快速发展为研究可燃气云的爆炸提供了更多便利的条件,尤其是CFD数值模拟方法的普遍应用。本文研究是在充分学习了解可燃气体爆炸的理论基础之上,并且借鉴相关研究成果,基于流体力学控制方程组、Realizablek-ε湍流方程和Eddy-Dissipation燃烧模型,建立了可燃气云爆燃的理论模型,对半径为0.5m的半球形乙炔-空气预混气云爆炸进行了三维数值模拟,并采用了密度基耦合求解器进行了数值求解,研究了爆炸超压随着时间变化的分布规律、最大超压与爆心距离的关系以及可燃气云燃料浓度对爆炸超压的影响,并把数值模拟结果与实验值进行了分析比较。论文选取了乙炔质量分数分别为5.3%、10.4%、13.3%和15.4%的预混气体,并得到不同质量分数的混合气云爆炸超压沿时间与空间的分布,模拟得到最大爆炸压力与实验结果吻合良好,最大相对偏差为13.79%;乙炔-空气爆炸的最危险质量分数为13.3%,其大约为化学计量比浓度的1.1倍,在这个浓度下,爆燃强度最大,同时破坏力也最严重;在气云爆炸初期,爆炸压力急剧增加,达到最大爆炸压力,在短期内有周期性的超压波不断向外扩散,且当气体浓度处于最危险质量分数时,产生的爆炸压力最大。在工业生产中,应尽量避免气体浓度达到其最危险质量分数,从而预防事故的发生。基于建立的可燃气云爆炸数值模型,进一步在开敞空间内放置障碍物,即在障碍物的诱导下,会产生极大破坏力的爆炸。因此,本文研究了有障碍物约束条件下对可燃气云爆炸场的影响,为提出可行的防爆、抑爆方案提供理论依据和数据支持。本文通过对内置障碍物条件下乙炔-空气爆炸进行了数值模拟,分析了障碍物对爆炸超压产生的加速机理、距点火源不同距离的障碍物对爆燃强度的影响以及障碍物的数量对爆炸超压的影响。通过研究得出,同一测点,相比无障碍物时,达到峰值超压的时间明显缩短,且最大爆炸压力大约为无障碍物时的6~8倍,最大爆炸压力可达25.33KPa,障碍物对爆炸超压具有较强的加强作用,可造成建筑物的严重破坏;当障碍物在气云内部时,可燃气云爆炸产生的峰值超压随着障碍物与点火源距离的增加而增加;当障碍物在可燃气云外部时,峰值超压逐渐有减小的趋势;可燃气体爆炸超压与障碍物数量呈正比,也就是随着障碍物数量的增加,障碍物对爆炸冲击波阻碍的程度就越大,则湍流程度越大,会产生更大的爆炸威力。
[Abstract]:With the rapid development of modern chemical production enterprises, serious accidents in production safety caused by the leakage of combustible gases occur frequently, and the explosion of combustible gases often directly results in serious casualties and property losses. One of the important reasons is that the research on the mechanism and laws of the explosion of combustible gases is insufficient. Up to now, many scholars have carried out in-depth research and Exploration on the explosion of combustible gases. However, because of the danger and complexity of explosion, the research on the law of explosion under different conditions is still a hot topic in this field. The rapid development of computer provides more convenient conditions for studying the explosion of combustible gas clouds, especially the universal application of CFD numerical simulation method. The flow equation and Eddy-Dissipation combustion model were used to establish the theoretical model of flammable cloud deflagration. The explosion of hemispherical acetylene-air premixed cloud with radius of 0.5m was numerically simulated in three dimensions. The density-based coupling solver was used to solve the problem. The distribution of explosive overpressure with time, the maximum overpressure and the maximum overpressure were studied. The relationship between detonation center distance and the influence of fuel concentration of combustible gas cloud on the explosion overpressure are analyzed and compared with the experimental results. The maximum explosion pressure obtained by simulation is in good agreement with the experimental results, the maximum relative deviation is 13.79%; the most dangerous mass fraction of acetylene-air explosion is 13.3%, which is about 1.1 times of the stoichiometric specific concentration. At this concentration, the detonation intensity is the largest and the destructive force is the most serious; at the initial stage of gas cloud explosion, the explosion pressure increases sharply, reaching to 13.3%. When the gas concentration is in the most dangerous mass fraction, the explosion pressure is the highest. In industrial production, the gas concentration should be avoided to reach the most dangerous mass fraction as far as possible, so as to prevent the occurrence of accidents. In this paper, the influence of obstacles on the explosion field of combustible clouds is studied, which provides theoretical basis and data support for putting forward feasible explosion-proof and explosion-suppression schemes. Acetylene-air explosion was simulated numerically. The acceleration mechanism of explosion overpressure caused by obstacles, the effect of obstacles at different distances from ignition source on detonation intensity and the influence of obstacles on Explosion Overpressure were analyzed. The maximum explosion pressure can reach 25.33 KPa. Obstacles can strengthen the explosion overpressure and cause serious damage to buildings. When the obstacles are inside the gas cloud, the peak overpressure caused by the explosion of combustible cloud increases with the distance between the obstacles and the ignition source. Additionally, when the obstacle is outside the combustible cloud, the peak overpressure decreases gradually, and the explosive overpressure of combustible gas is proportional to the number of obstacles, that is, with the increase of the number of obstacles, the obstacle hinders the explosive shock wave to a greater extent, the greater the turbulence flow, will produce greater explosive power.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X928.7
本文编号：2212926
[Abstract]:With the rapid development of modern chemical production enterprises, serious accidents in production safety caused by the leakage of combustible gases occur frequently, and the explosion of combustible gases often directly results in serious casualties and property losses. One of the important reasons is that the research on the mechanism and laws of the explosion of combustible gases is insufficient. Up to now, many scholars have carried out in-depth research and Exploration on the explosion of combustible gases. However, because of the danger and complexity of explosion, the research on the law of explosion under different conditions is still a hot topic in this field. The rapid development of computer provides more convenient conditions for studying the explosion of combustible gas clouds, especially the universal application of CFD numerical simulation method. The flow equation and Eddy-Dissipation combustion model were used to establish the theoretical model of flammable cloud deflagration. The explosion of hemispherical acetylene-air premixed cloud with radius of 0.5m was numerically simulated in three dimensions. The density-based coupling solver was used to solve the problem. The distribution of explosive overpressure with time, the maximum overpressure and the maximum overpressure were studied. The relationship between detonation center distance and the influence of fuel concentration of combustible gas cloud on the explosion overpressure are analyzed and compared with the experimental results. The maximum explosion pressure obtained by simulation is in good agreement with the experimental results, the maximum relative deviation is 13.79%; the most dangerous mass fraction of acetylene-air explosion is 13.3%, which is about 1.1 times of the stoichiometric specific concentration. At this concentration, the detonation intensity is the largest and the destructive force is the most serious; at the initial stage of gas cloud explosion, the explosion pressure increases sharply, reaching to 13.3%. When the gas concentration is in the most dangerous mass fraction, the explosion pressure is the highest. In industrial production, the gas concentration should be avoided to reach the most dangerous mass fraction as far as possible, so as to prevent the occurrence of accidents. In this paper, the influence of obstacles on the explosion field of combustible clouds is studied, which provides theoretical basis and data support for putting forward feasible explosion-proof and explosion-suppression schemes. Acetylene-air explosion was simulated numerically. The acceleration mechanism of explosion overpressure caused by obstacles, the effect of obstacles at different distances from ignition source on detonation intensity and the influence of obstacles on Explosion Overpressure were analyzed. The maximum explosion pressure can reach 25.33 KPa. Obstacles can strengthen the explosion overpressure and cause serious damage to buildings. When the obstacles are inside the gas cloud, the peak overpressure caused by the explosion of combustible cloud increases with the distance between the obstacles and the ignition source. Additionally, when the obstacle is outside the combustible cloud, the peak overpressure decreases gradually, and the explosive overpressure of combustible gas is proportional to the number of obstacles, that is, with the increase of the number of obstacles, the obstacle hinders the explosive shock wave to a greater extent, the greater the turbulence flow, will produce greater explosive power.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X928.7
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1 党福辉;开敞空间可燃气云爆炸数值模拟研究[D];天津理工大学;2017年
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