【作者】 张增亮；

【导师】 林柏泉；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2013， 博士

【摘要】 煤矿开采是我国的支柱产业，瓦斯爆炸是威胁煤矿安全生产的主要因素。我国的大多数矿井属于高瓦斯矿井，且由于受地质条件限制及生产需要，矿井设计和布置结构复杂，所以，瓦斯爆炸的形成和发展过程中会受到众多复杂结构和复杂条件等因素的影响，同时爆炸所表现出的特征也呈现复杂性和特殊性，为煤矿瓦斯爆炸防治增加了难度。因此，探索煤矿各种复杂结构及复杂条件下瓦斯爆炸的特征及成因，成为有效防治煤矿瓦斯爆炸的关键。针对这一实际问题，综合运用燃烧爆炸学、化学反应动力学、流体力学、工程力学等多学科知识，进行了620次管道模拟实验，分别拍摄了关于爆炸火焰传播的高速摄影50个、高速纹影80个，同时运用多种方法对煤矿中存在的几种复杂结构及其复杂条件下的瓦斯爆炸作用机制进行了对比分析研究，得出了以下创新性的成果。（1）研究网格状障碍物对瓦斯爆炸的影响通过对几种网格状障碍物对比研究发现，火焰通过圆孔障碍物时，相对方孔障碍物，形成较小的火焰速度和爆炸压力，这是爆炸扩张和流体流动总是试图保持最小体积即球形决定了圆孔易于火焰扩张通过的结果；当网格障碍物的小孔尺寸小于火焰的临界熄爆直径，甚至小于临界安全间隙时，火焰经过障碍物会发生熄灭，但过瓦斯感应期后，在小孔另一侧会发生复燃。同时，由于气流从小孔喷出及复燃延迟相对较慢，而爆炸过程相对较快，导致气流穿过障碍物后会发生一连串的小爆炸，而且网孔越细，小爆炸愈多。由于气流通过网格障碍物产生喷射冲击作用，同时在障碍物本身的梳理扰动作用下，致使产生强烈湍流，火焰速度剧增，压力骤升。从高速摄影和高速纹影图像看，火焰通过障碍物或过障碍物虽熄灭但重燃后，由于障碍物形状不同，火焰形状严重分化，火焰前锋或因浮力作用上扬、或因气流浓度增大而下垂，同时很快分化形成tulip结构。（2）模拟研究矿井风门、密闭墙等对瓦斯爆炸的影响通过模拟实验结果看，当爆炸突破薄膜时，火焰速度和压力暂时下降，能量有所损失，但会因预压、预热作用产生更大的激波和高热，极大地提高爆炸压力和火焰速度。薄膜破裂会因火焰传播引起“异地二次爆炸”，还会反冲逆袭引起“原地二次爆炸”。此外，通过综合几种障碍物来看，薄膜障碍物对爆炸的激励作用最大、最强，进一步说明了加固相关设施的必要性和重要性。（3）瓦斯爆炸对矿井硐室的影响通过运用不同内径的管道模拟瓦斯爆炸对矿井硐室的影响，发现无论在硐室模拟管道开口或闭口但易被突破的的情况下，内部瓦斯爆炸会产生远大于主干管道的压力和压力上升速度，并产生强力回冲现象，造成二次破坏或形成二次爆炸点火源。另外，模拟硐室门窗出现小缝隙或孔洞的情况下，火焰经过时会出现熄灭、复燃现象，同时回冲过程中再次出现熄灭、复燃现象，这种反复激励作用，会导致更大的爆炸力。所以硐室及其门窗等要从强度、材料、密封性等诸方面周密设计制作，隔断热量和火焰传入硐室内部。（4）通过实验和流体力学理论模拟研究巷道各种瓦斯填充情况下，拐弯结构对瓦斯爆炸的影响随着拐弯内折角度增大，主干管道段压力明显有增大的趋势，而经过拐弯后的火焰速度和压力衰减呈加剧趋势，当内折角度增大到一定程度，可发生局部熄灭或完全熄灭，造成火焰速度和压力衰减更加加剧。此外，拐弯阻力造成的能量损失以及开口处的稀疏波影响也是导致火焰速度和压力衰减的重要原因。一般在直管道中，开口状况下60%以上的瓦斯填充率产生的爆炸压力和火焰速度与管道全充满瓦斯时产生的压力和火焰速度基本一样。但在拐弯管道中，激波反射形成回冲激波，大大抑制火焰速度，并使管道内压强叠加增大，同时，回冲激波使直管道前段的空气回冲与前行的瓦斯混合稀释，使瓦斯燃烧受到更大影响，火焰速度进一步下降，由此造成压力相对有所下降。当拐弯前火焰速度为超声速时，经过拐弯后，凹壁侧的火焰速度小于凸壁侧的火焰速度，而凹壁侧的压力大于凸壁侧的压力；在拐弯前，管道上侧压力大于下侧压力。当拐弯前火焰速度为亚声速，火焰速度和压力变化规律与超声速情况下的结论正相反。本研究成果将进一步丰富瓦斯爆炸理论，为煤矿巷道结构及设施的布置提供有益的启示和借鉴，对煤矿复杂结构及复杂条件下的瓦斯爆炸防治发挥指导作用。根据本研究成果发表相关论文9篇，其中SCI2篇，EI源刊3篇，国际会议论文3篇，中文核心期刊1篇。更多还原

【Abstract】 Coal mining is the pillar industry of our country, and gas explosion is the mainfactor which threatens coal-mine safety production. Most of coal mines in our countrywere considered to be high methane mines. Limited by the special geologic condition andthe demand for production,coal mines usually were designed and distributedcomplicatedly,therefore,the formation and development process of gas explosion may beinfluenced by complicated structures and conditions. Besides gas explosion itself showsthe characteristics of complicacy and particularity, which make it more difficult toprevent gas explosion. Thus，research on the characteristics and causes of gas explosionunder complicated structures and conditions is the key to the prevention and control ofgas explosion.According to the real problem,the multidisciplinary knowledge, such as combustionand explosion, chemical reaction kinetics, fluid mechanics, engineering mechanics wereused comprehensively,620simulation experiments in tube were carried out,50high-speed photographies and80high-speed schlierens were taken, and a variety ofmethods were adopted to comparatively study gas explosion mechanism in severalcomplicated structures and conditions underground coal mine. Thus, the followinginnovative results were obtained.(1)Influence of grid-shape obstacles on gas explosion in coal mineThe flame shows a lower speed, expand more easily and induced a smaller pressurewhen it passes through a round hole obstacle compared to a square hole one.If the size ofthe obstacle hole was less than the critical misfire diameter, or even less than the criticalsafety gap, the flame would extinguish and reignite again beyond the obstacle afterinduction periods of gas explosion. And because of the lag between airstream erupts fromthe obstacle and induction periods of gas explosion, a series of small explosions emergedafter airstream passing through the obstacle, and the smaller the grids were, the moreexplosions would be. As the result of jets and impacts of airstream while it goes thoughthe holes of the obstacle, together with the combing perturbation effect of the obstacle,intense turbulence will be generated.Therefore, flame speed will increase rapidly, andpressure will also rise sharply.According to high-speed photographs and high speed schlieren photographs, theflame was badly deformed and flame front moved upward due to the buoyancy effect ordownward owning to the increased concentrations when the flame get through the obstacles of different shapes, and evolved into tulip structure soon.(2) Effect of damper or airtight wall on gas explosionAluminum film was shaped to simulate the damper or airtight wall, the resultsshows that when the flame breaks through the film, the flame speed and pressuredescends temporarily with considerable energy loss,but explosion will be more powerfuland destructive because of preloading and preheating effect, which promoted a higherexplosion pressure and flame speed. The rupture of the film may lead to “allopatrysecondary explosions” as a result of flame propagation, and also” autochthonoussecondary explosions” caused by recoil and counterattack effects of the flame. Inaddition, the most incentive role of obstacles was to enhance explosion effect bycomparing with the situation with different kinds of obstacles, which proved thenecessity and importance of reinforced related structures.(3) Influence of gas explosion on mine chamberDifferent diameter of tubes was used to simulatively study gas explosion in thechamber. The results shows that,whether the tubes were open or closed, gas explosion inchamber would produce a considerably higher pressure and rate of pressure rise than thatin the trunk tube,and a strong backwash was occurred, which may cause a secondarydamage or the ignition source of secondary explosion. The flame would extinguish andreignite when flame arrived the simulated cracks or holes in the chamber,and it wouldextinguish and reignite again when the flame rushed back The repeated incentive resultedin more powerful explosions. Therefore,great importance must be attached to intensity,material, sealing and some other aspects to insulate from heat and flame when designingthe chamber.(4)Explosion propagation law of various filling-ratio gases at the bend of tubeExplosion propagation law of various filling-ratio gases at the bend of tube wasstudied by the experiment and the theory of hydromechanics.The results shows that, withthe increase of the turned angle of the tube, there is an evident uptrend of the pressure inthe trunk tube and a severely attenuation trend of the flame speed and pressure after thecorner of the tube. When the angel turns to certain extent, the flame is partially or totallyextinguished,and further leads to a even steeper attenuation of the flame speed andpressure. Moreover rarefaction wave and the resistance of the tube corner which causedloss in energy could partly account for the attenuation as well.Generally, explosion pressure and flame speed of more than60%filling-ratio gas isbasically the same as those of100%filling-ratio gas in the straight tube. However, in a bend tube, backwash shock wave generated by reflection greatly reduces methane flamepropagating speed and produces pressures superposition as well. At the same time,backwash shock wave would push back the air in front of the straight tube to dilute themoving methane, which has significant impact on gas combustion, making the flamespeed even lower,and pressure drop relatively.If flame speed before the tube corner increases to the supersonic state, flame speedafter the corner in concave wall side is less than that in convex wall side, while pressurein concave wall side is larger than that in convex wall side. If flame before the tubecorner is a subsonic flow, conclusions were completely opposite.The research findings would further enrich gas explosion theory, offer beneficialenlightenment and reference to the layout of the structure of roadway and some facilitiesunderground coal mine, and play a guiding role for gas explosion prevention under manycomplex structures and conditions.In addition,9papers were published based on the results of the study, including2SCI and3EI papers,3international conference papers and1article published in nationalcore periodical.更多还原