不同角度分叉管道内氢气-空气爆轰传播特性

在3种角度分叉管道内开展化学计量比氢气-空气爆轰实验，采用自制的火焰传感器和烟迹法分别获得了爆轰波传播速度和胞格结构，探究了不同角度管道分叉对爆轰传播的影响。结果表明：氢气-空气爆轰在经过分叉三通时受分叉口稀疏波影响导致爆轰波衰减解耦，但随着入射激波与下游管道壁面碰撞，逐渐由规则反射向马赫反射转变，最终完成重起爆过程。其中，直通支管内爆轰衰减主要受支管入口面积的影响，随着分叉角度增大，入口面积减小，爆轰衰减程度和重起爆距离也随之减小；而分叉支管内，爆轰衰减受支管入口面积与入口渐扩程度共同影响，但随着分叉角度的增大，入口面积变为主要影响因素。不同角度分叉管内的实验结果均表明，初始压力升高能显著提高爆轰稳定性，从而削弱分叉几何结构的影响。

Propagation characteristics of hydrogen-air detonation in bifurcated tubes with different angles

Study on propagation characteristics of detonation in bifurcated tubes is of great significance to the safety protection of gas explosion in pipelines and engineering application. The propagation states of detonation vary with the geometrical structure when passing through the bifurcated tee. Based on the detonation circular test tube, the stoichiometric hydrogen-air mixture gas with 29.5% H₂ in the volume fraction under different initial pressures was ignited by a 10-kV double high-voltage electrode to be detonated before entering the 30°, 45° and 90° bifurcation tees, respectively. The propagation characteristics of the detonation in the bifurcated tubes were analyzed based on the propagation velocity and cellular structure evolution characteristics obtained from the feedback signals of flame sensors and smoke-foils records. The results show that the H₂/air detonation will decay when it passes through a bifurcated tee which is affected by rarefaction wave, but it is only a local phenomenon. The detonation re-initiation is gradually completed from regular reflection to Mach reflection after collision of incident shock wave and wall. In the straight branch tube, the detonation decay is mainly affected by the inlet area of the collateral branch tube. With the increase of the bifurcation angle, the inlet area decreases, and the detonation decay and re-initiation distance decrease as well. In the collateral branch tube, the detonation decay is affected by both the inlet area of the collateral branch tube and the gradual expansion of the section. When the bifurcated angle exceeds the critical value, the inlet area becomes the main influence factor. In addition, it is proved that increasing the experimental initial pressure of premixed gas can significantly improve the detonation stability and weaken the influence of bifurcation geometry. The mechanism of detonation decay and re-initiation in the bifurcated tubes is clarified by this study, which enriches the study of detonation diffraction and contributes to provide a scientific reference for engineering application and taking proper measures of explosion safety protection of gas pipelines as well.