摘要:
为了有效预测和控制封闭空间内油气爆炸的后果，进而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。在控制初始油气浓度以及点火位置和点火能量不变的情况下，开展了不同长径比、不同体积和不同长度的密闭方形管道条件下油气的爆炸超压特性实验。实验结果表明，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这三个阶段，其反映了反应速率与热损失之间的动态变化关系。体积不变（21.2L），随着长径比的增加（从7.1增加至35.7），最大超压下降47.5%（从472.9kPa下降至248.5kPa）、平均超压上升率下降73.5%（1359kPa·s-1下降到360kPa·s-1）、最大超压上升速率下降66.4%（从3204kPa·s-1下降至1078kPa·s-1）及爆炸威力下降86.2%（从643 (kPa)2/ms下降到89 (kPa)2/ms），这是由于管口面积的变化（从207cm2减小到71cm2）影响反应速率以及管道内表面积的变化（从629cm2增加到1022cm2）影响热损失。进一步分析试验结果发现，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 mixtures explosions in enclosed spaces, and thereby reduce the casualties and property losses caused by accidents, this study had investigated the relationship between the explosive overpressure characteristics of fuel-air mixtures and the spatial scale of explosions. The experiment carried out closed square pipes with varying length-to-diameter ratios, volumes and lengths to examine the impact of fuel-air mixtures explosive overpressure characteristics by keeping the initial oil and gas concentration, ignition position, and ignition energy constant. The experimental results showed 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. Under the same volume (21.2L), with the increase of length-diameter ratio (from 7.1 to 35.7), the maximum overpressure decreased by 47.5% (from 472.9kPa to 248.5kPa), and the average overpressure rise rate decreased by 73.5% (from 1359kPa·s-1 to 360kPa·s-1), and the maximum overpressure rise rate reduced by 66.4% (from 3204kPa·s-1 to 1078kPa·s-1), and the explosion power lessened by 86.2% (from 643 (kPa)2/ms to 89 (kPa)2/ms), which is attributed to the change in the nozzle area (from 207cm2 to 71cm2) affecting the reaction rate and the change in the internal surface area of the pipeline (from 629cm2 to 1022cm2) affecting the heat loss. Further analysis of the experimental results reveals that the changes in the nozzle area affecting the flame front area and reaction rate directly, impacts on the maximum overpressure more directly and significantly. While, the changes in the inner surface area has 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 relatively attenuation.
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