甲烷体积分数及巷道结构对甲烷爆炸特性影响研究

Study on influence of methane′s volume fraction and roadway structure on methane explosion characteristics

为明确甲烷体积分数及巷道结构对甲烷-空气爆炸特性的影响机制,采用Fluent软件建立3种不同结构的巷道模型,对甲烷体积分数分别为6%、9.5%和13%条件下的巷道甲烷爆炸过程进行数值计算,分析爆炸压力和温度的变化特性以及火焰的传播特性。结果表明:当甲烷的体积分数为9.5%时,直巷道中冲击波峰值压力及爆炸温度最高;随着测试距离的增加,冲击波峰值压力不断降低,并且符合指数衰减特征;不同巷道结构甲烷爆炸后压力峰值的差异主要出现在弯道处,其冲击波峰值压力大小为90°巷道>直巷道>分叉巷道;分叉巷道中经过拐角后的冲击波峰值压力明显下降,对冲击波阻碍作用显著;此外,当冲击波进入弯道并沿壁面传播时,受压缩波、稀疏波及反射波等多波系共同影响,火焰沿壁面传播特性发生改变。

In order to clarify influence of methane′s volume fraction and roadway structure on methane-air explosion characteristics,three kinds of tunnel models with different structures were established by using Fluent software.Then,numerical calculations of explosion process in roadway were carried out for methane at volume fraction of 6%,9.5%,and 13%,and change laws of explosion pressure and temperature and propagation characteristics of flame were analyzed.The results show that when the volume fraction is 9.5%,peak pressure of shock wave and explosion temperature are the highest in straight roadway.With the increase of test distance,the peak pressure decreases continuously in conformity to exponential attenuation law.The difference in pressure peaks after methane explosion for different roadway structures mainly appears at the bend,ranking as 90°roadway>straight roadway>bifurcation roadway.Peak pressure is significantly reduced after passing through bend in bifurcated roadway,which has a significant hindering effect on shock wave.In addition,when it enters the bend and propagates along walls,it will be affected by compression wave,sparse wave and reflected wave,and flame propagation characteristics along walls will change.