惰性气体和水蒸气对长直空间燃气爆炸超压及其振荡的抑制作用

Inert Gas and Water Vapor Suppressing Overpressure and Its Oscillation of Gas Explosion in Long Straight Space

长直空间燃气爆炸超压及其振荡将对人员和结构安全产生不利影响。为减轻燃气爆炸危害,基于CFD软件FLACS建立了长直管道空间燃气爆炸数值模型,并对模型进行了验证。利用已验证的数值模型,研究了添加不同体积分数CO_(2)、N_(2)和水蒸气的化学当量比CH_(4)/空气混合气体的爆炸,讨论了惰性气体和水蒸气的体积分数对爆炸超压及其振荡的影响,并对比了3种气体的抑爆效果。结果表明:CO_(2)、水蒸气和N_(2)的体积分数每增加10%,密闭管道气体爆炸的最终超压将分别下降81、47、65 kPa,尾端泄爆管道分别下降24、25、20 kPa,3种气体的体积分数分别为25%、26%、30%时,爆炸被完全抑制;CO_(2)、水蒸气和N2均能有效抑制爆炸超压的振荡,压力振幅和压力振荡频率均随添加气体体积分数的增加而减小;CO2对爆炸超压及其振荡的抑制效果最好,水蒸气次之,N2最弱,这与3种气体的物理特性及其抑爆机理的差异有关。

The overpressure and its oscillation of gas explosion in long straight space will endanger personnel and structures.In order to reduce the potential hazards,a numerical model of gas explosions in long straight tube was established based on the CFD software FLACS and was verified by using the existing experimental data.Based on the validated numerical models,the suppression of CO_(2),N_(2) and water vapor on the CH_(4)/air mixture explosions with stoichiometric concentration was investigated.The influence of the volume fraction of inert gas and water vapor on the explosion overpressure and its oscillation was considered and discussed.It is shown that for every 10%increase in the volume fraction of CO_(2),water vapor and N2,the final overpressure of the gas explosion in the closed tube drops by 81,47 and 65 kPa,the final overpressure in the end-vented tube decreases by 81,47 and 65 kPa.When the volume fractions of CO_(2),water vapor and N2 are 25%,26%,and 30%,respectively,the explosion is completely suppressed.CO_(2),water vapor and N_(2) can effectively suppress the oscillation of explosive overpressure,both the pressure amplitude and the pressure oscillation frequency decrease with the increase of the volume fraction of added gas.CO_(2) has the best suppression effect on explosion overpressure and its oscillation,followed by water vapor,and N_(2) is the weakest.This phenomenon is related to the differences in the physical properties of the three gases and the suppression mechanisms.