Influence of length-diameter ratio and volume on hydrocarbon explosion overpressure characteristics in a closed square pipeline
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摘要: 为了有效预测和控制封闭空间内油气爆炸的后果,减少事故导致的人员伤亡和财产损失,对油气爆炸的超压特性与爆炸发生空间尺度的关系进行了研究。在控制初始油气体积分数、点火位置和点火能量不变的情况下,开展了不同长径比和体积的密闭方形管道条件下油气的爆炸超压特性实验。实验结果显示,在爆炸过程中,超压上升的速率经历急剧增长期、持续震荡期和衰减终止期3个阶段;管口面积的减小和内表面积的增加会导致最大超压、平均超压上升速率、最大超压上升速率和爆炸威力下降。进一步分析实验结果发现,管口面积变化会直接影响火焰前锋面积和反应速率,对最大超压的影响更为直接和显著,而内表面积变化对最大超压的影响相对间接,是通过调节能量传递和热损失来起作用。此外,管道长度是影响到达最大超压时间的关键因素,管道增长不仅增加了热损失,还使反射波与入射波的叠加时间点延后,并且反射波的能量会相对较多地衰减。Abstract: In order to effectively predict and control the consequences of fuel-air mixture explosions in enclosed spaces and thereby reduce the casualties and property losses caused by accidents, the relationship between the explosive overpressure characteristics of fuel-air mixtures and the spatial scale of explosions was investigated. Closed square pipes with varying length-diameter ratios, volumes, and lengths were used to examine the impact of fuel-air mixture explosion overpressure characteristics by keeping the initial oil and gas concentration, ignition position, and ignition energy constant. The experimental results show that the rate of overpressure rise goes through three stages: a rapid increase period, a continuous oscillation period, and an attenuation termination period, which reveals the dynamic relationship between reaction rate and heat loss. The reduce of the nozzle area and the increase of the internal surface area of the pipeline can both lead to the decrease of the the maximum overpressure, the average overpressure rise rate, the maximum overpressure rise rate, and the explosion power. The further analysis of the experimental results reveals that the change in the nozzle area will directly affect the flame front area and reaction rate, with a more direct and significant impact on the maximum overpressure. The changes in the inner surface area have a relatively indirect effect on the maximum overpressure by regulating energy transfer and heat loss. Additionally, pipeline length is a crucial factor affecting the time to reach maximum overpressure. The increase of the pipeline not only increases the heat loss but also delays the superposition time point of the reflected wave and the incident wave, with the energy of the reflected wave undergoing relative attenuation.
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表 1 密闭管道的尺寸
Table 1. Size of closed pipes
管道 L/cm D/cm V/L L/D 管道 L/cm D/cm V/L L/D 管道 L/cm D/cm V/L L/D 1 102 14.4 21.2 7.1 3 300 8.4 21.2 35.7 5 228 11.4 29.6 20.0 2 163 11.4 21.2 14.3 4 168 8.4 11.9 20.0 6 288 14.4 59.7 20.0 表 2 内表面积和管口面积对最大超压的影响
Table 2. The influence of internal surface area and nozzle area on the peak overpressure
管道 L/cm D/cm 内表面积/cm2 管口面积/cm2 pmax/kPa 2 163 11.4 769 130 400.8 3 300 8.4 1022 71 248.5 4 168 8.4 579 71 368.7 5 228 11.4 1066 130 352.8 -
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