Gas explosion inside a pipe is a complex phenomenon. Extensive studies have been carried out to investigate factors governing to the explosion development i.e. the flame speed and the maximum pressure. However, most of the works are limited to open straight pipes. Worst, the effect of the obstructions on the explosion severity is still unclear. Most of the gases used in the industrial piping are highly combustible and has a potential to initiate detonation hazard. In this work, gas explosions inside closed pipes are considered. Experimental and Computational Fluid Dynamic (CFD) analyses using FLACs are adopted to investigate the physical and dynamic behaviour on gas explosion development in pipes. Hydrogen, acetylene, ethylene, propane and methane were used as fuels. The effect of pipe configuration (straight and 90 bend pipe) with different length to diameter ratio (LID) was investigated. From the results, it was observed that the presence of 90 degree bend enhances the explosion severity by a factor of 1.03-3.58 as compared to that of the straight pipe. Based on the simulation analysis, the compression effect at the bending region and at the end of the pipe plays an important role to attenuate the burning rate, which resulting to a higher flame speeds and hence, increases the overpressure.udInterestingly, a maximum overpressure of 14 barg with flame speed of 700 mis was observed in the smaller pipe of L/D=40 with acetylene fuel which indicated that theuddetonation-like event take place. The ability of' the flame to quench becomes insignificant in a smaller pipe, promoting a strong interaction of the fast flame and turbulence, particularly at the bending. This phenomenon amplifies the mass burning rate, increases the flame speeds and leading to a higher pressure rise. From theudresults, it shows that fuel reactivity and pipe size and configuration gives a significant effect to the overall overpressure and flame acceleration development which can lead to a catastrophic explosion.
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机译：管道内的气体爆炸是一个复杂的现象。已经进行了广泛的研究来研究控制爆炸发展的因素，即火焰速度和最大压力。但是，大多数工程仅限于开放式直管。最糟糕的是，障碍物对爆炸强度的影响仍不清楚。工业管道中使用的大多数气体都是高度可燃的，并且有引发爆炸危险的潜力。在这项工作中，考虑了封闭管道内部的瓦斯爆炸。采用FLAC进行实验和计算流体动力学（CFD）分析，以研究管道中气体爆炸发展的物理和动态行为。氢气，乙炔，乙烯，丙烷和甲烷用作燃料。研究了不同的长径比（LID）的管道配置（直管和90弯管）的影响。从结果可以看出，与直管相比，90度弯曲的存在将爆炸严重性提高了1.03-3.58倍。根据模拟分析，在弯曲区域和管道末端的压缩效果在减弱燃烧速率方面起着重要作用，从而导致更高的火焰速度，从而增加了过压。 ud有趣的是，最大过压在L / D = 40的较小管中使用乙炔燃料时，观察到14 barg的火焰速度为700 mis，这表明发生了类似“爆轰”事件。在较小的管道中，火焰的淬灭能力变得微不足道，特别是在弯曲处，促进了快速火焰和湍流的强烈相互作用。这种现象会放大质量燃烧率，增加火焰速度并导致更高的压力上升。从结果可以看出，燃料的反应性，管道的尺寸和配置对总体超压和火焰加速的发展有重大影响，这可能导致灾难性爆炸。
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