油气在顶部含弱约束结构受限空间内的爆炸特性

Explosion of gasoline/air mixture in confined space with weakly constrained structure at the top

建立了顶部含有弱约束结构的受限空间油气爆炸实验系统,并对含有弱约束的受限空间中油气爆炸特性进行实验研究,获得超压变化规律及火焰发展特征。结果表明:(1)容器内部超压受泄流、外部爆炸、火焰扩张等因素的影响,出现多个峰值,并伴以强烈的振荡;容器外部超压随着距离的增大而减小,且竖直方向超压大于水平方向超压。(2)与无约束爆炸相比,弱约束结构对爆炸的影响主要体现在对爆炸超压的增强效应和对爆炸发展速率的滞后效应。(3)爆炸超压随着油气体积分数的增加先增大后减小,最大超压所对应的初始油气体积分数为1.79%。(4)容器外火焰发展过程分为初级燃烧阶段、过渡燃烧阶段、次级燃烧阶段,由于受Rayleigh-Talor不稳定、Helmholtz不稳定、斜压效应的影响,火焰出现褶皱和卷曲,最大火焰高度和直径分别为0.8和0.55m。

An experimental system of a confined space with a weakly constrained structure at the top was established. A series of gasoline/air mixture explosion experiments were conducted, and overpressure characteristics as well as flame behaviors were obtained. The results show that the internal overpressure exhibited a phenomenon of multi-peaks and pressure oscillations, induced by such factors as venting, external explosion, flame extension, etc. The value of the external overpressure decreased obviously with the increase of the distance from the weakly constrained structure, and the value along the vertical direction was larger than that along the horizontal direction. The impact of the weakly constrained structure was mainly reflected in the enhancement effect on the overpressure value and the lagging effect on the development rate of the explosion. The overpressure value showed the tendency to increase at first and then to decrease with the increase of the volume fraction of the gasoline/air vapor volume corresponding to the maximum overpressure, which is 1. 79%. The flame propagation process involves three stages, i.e. stages of primary combustion, transitional combustion and secondary combustion. Affected by the Rayleigh instability, the Helmholtz instability and the baroclinic effect, the flame front was twisted and wrinkled, and the maximum height and maximum diameter were 0.80 and 0.55 m, respectively.