Effects of bilateral branches structure on characteristics of gasoline-air mixtures explosion overpressure and flame behavior in a semi-confined space

doi:10.16085/j.issn.1000-6613.2017-2522

Abstract

Abstract: In order to investigate the overpressure characteristics and flame behavior of gasoline-air mixtures explosion in a semi-confined space with double side branches structure, the explosion overpressure peaks in straight and bilateral branches pipes under different initial gasoline-air mixtures concentrations were studied. Semi-open plexiglass pipes were used to visualize the flame propagation behavior. Results showed that:①there existed three typical pressure peaks denoted as p₁、p₂ and p_max during the gasoline-air mixture explosions in the semi-open pipe and the magnitude of p₁ was just associated with the fracture constant of the polyethylene film at the pipe exit and p₂ was related to branch pipe pressure relief while p_max was affected by the intensity of explosion inside the pipe and flame acceleration. ②The branch pipe has an intensive effect on the explosion strength. With the increase of gasoline-air mixtures concentration, the strengthening effect firstly increases and then decreases, and the strengthening effect is most intense at the concentration of 1.4% to 1.8%. ③The flame occurs at the branch structure with significant bending and folding, which increases the flame area, increases the combustion rate, accelerates the heat transfer efficiency of the flow field, induces the sharp increase of explosion intensity, and at the same time, the flame propagation speed and the maximum flame front position are increased. ④The flame presents a "hemispherical flame——fingertip flame——planar flame——spray flame" morphology changes in the pipe containing the bilateral branch structure.

Key words: gasoline-air explosions, explosion overpressure, flame speed, branch structure, mixtures

摘要： 为研究含有双侧分支结构受限空间内油气泄压爆炸超压和火焰演变特性，进行了不同初始油气体积分数工况下含有双侧分支结构受限空间和长直受限空间内的对比实验。研究结果表明： ①爆炸超压曲线会出现3个典型的超压峰值p₁、p₂、p_max，其中p₁的形成与管道开口端密封材料瞬时破裂有关，p₂与分支结构泄压有关，而p_max受管道内部爆炸强度与火焰加速协同效应影响。②分支结构对爆炸超压有强化作用，当油气体积分数在1%～2%区间，爆炸超压强化程度先增强后减小，且在1.4%～1.8%之间最为强烈。③火焰在分支结构处发生显著的弯曲、褶皱变形，这增大了火焰面积，提高了燃烧速率，加速了流场的传热传质效率，诱导爆炸强度的急剧增大，同时提高了火焰传播速度并增大了最大火焰锋面位置。④火焰在含有双侧分支结构的管道内呈现“半球形火焰——指尖形火焰——平面状火焰——浪花状火焰”形态变化。

关键词: 油气爆炸, 爆炸超压, 火焰速度, 分支结构, 混合物

CLC Number:

X932

DU Yang, LI Meng, LI Guoqing, WANG Shimao, ZHANG Peili, QI Sheng, WEI Shihao. Effects of bilateral branches structure on characteristics of gasoline-air mixtures explosion overpressure and flame behavior in a semi-confined space[J]. Chemical Industry and Engineering Progress, 2018, 37(07): 2557-2564.

杜扬, 李蒙, 李国庆, 王世茂, 张培理, 齐圣, 韦世豪. 含双侧分支结构受限空间油气泄压爆炸超压特性与火焰行为[J]. 化工进展, 2018, 37(07): 2557-2564.

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