半密闭空间油气爆炸初期火焰特性研究

Study on initial flame characteristics of gasoline-air mixtures explosion in semi-confined space

为了研究半密闭空间内部油气着火爆炸初期火焰特性,进行了不同油气体积分数下的油气着火爆炸实验,通过高速摄影等技术手段对爆炸过程中火焰形态进行了捕捉,分析了不同油气体积分数下爆炸初期火焰着火模式、火焰形态、传播过程和火焰浮力稳定性的变化规律。结果表明:油气体积分数为决定容器内部着火模式的关键因素,随着油气体积分数的逐渐增大,着火模式呈现出燃烧-爆炸-爆燃后持续燃烧的转变;爆炸下的火焰具有明显的分区现象,而其他的着火模式则没有;随着油气体积分数的增加,越靠近化学当量比,纵向和横向火焰阵面速度越大;油气体积分数小于等于1.1%或大于等于2.6%时,火焰稳定性受浮力影响显著。

In order to investigate the flame characteristics in the initial stage of gasoline-air mixtures explosion in the semi-confined space,the experiments of gasoline-air ignition and explosion under different gasoline-air volume fractions were carried out.The flame morphology during the explosion process were captured by the high-speed photography and other technical methods,and the change laws of flame ignition modes,flame morphology,propagation process,stability of flame buoyancy in the initial stage of explosion under different gasoline-air volume fractions were analyzed.The results showed that the gasoline-air volume fraction was the key factor determining the internal ignition mode in the vessel.With the gradual increase of the gasoline-air volume fraction,the ignition mode presented the transition to the continuous combustion after the combustion-explosion-deflagration.The flame under the explosion had an obvious partition phenomenon,while the other modes of ignition had not.With the increase of the gasoline-air volume fraction,the closer to the stoichiometric ratio,the larger the front speeds of the longitudinal and horizontal flame.The flame stability was significantly affected by the buoyancy when the gasoline-air volume fraction was less than or equal to 1.1%or larger than or equal to 2.6%.