对称障碍物条件下瓦斯爆炸火焰与压力波耦合作用研究

Coupling effect of the flame propagation and the pressure wave on the gas explosion in the square duct under the condition of symmetric obstacles

为了研究对称障碍物条件下瓦斯爆炸压力波与火焰传播的耦合作用,在150 mm×150 mm×1 700 mm的有机玻璃瓦斯爆炸管道中,距离点火端不同距离安装0.5阻塞率的对称障碍物,进行8.5%甲烷体积分数的爆炸试验,采集瓦斯爆炸的超压信号并同步拍摄火焰传播图像。结果表明：火焰穿越板式对称障碍物的过程经历了火焰加速、火焰降速到火焰再加速的过程,火焰降速的时间仅为5 ms。距离点火焰源不同长度的对称障碍物在火焰加速过程中的作用存在明显差异,近点火源的障碍物作用主要为诱导湍流,远离点火源的障碍物作用主要为湍流增强。

The present paper is inclined to turn its experimental study orientation on the coupling effect of the flame propagation process and the pressure wave on the gas explosion in the square duct under the condition of the symmetric obstacles. As is known, the experimental system mainly consists of the explosion pipe, the ignition source, the pressure sensor, the high-speed camera and the obstacles, whereas the explosion pipe made of organic glass is usually placed horizontally to operate the high-speed camera dynamically. The said experimental study has to be done in a square-shaped duct with the symmetric obstacles installed to explore the couple effects of the gas explosion flame propagation and the over-pressure. To study the effect of the site where the obstacles are installed, we have chosen the three on-site installed obstacles in different distances from the ignition source, the right ends of which are sealed up with the stainless steel plate whereas the left ends-with a film seal to be used as the pressure relief surface in the explosion system. On its opposite, the symmetric obstacles with the half blockage could be used to study the effects of the obstacles on the acceleration of the gas （8. 5 % volume fraction methane） explosion flames. Thus, the aforementioned installation has to be established to collect the image of the explosive gas flame and the over pressure signals through the fast flame speeds simultaneously. The experimental results show that the flame passing through the plate symmetrical obstacles has experienced a process of the flame acceleration and deceleration in the entire acceleration process, though the duration of the flame deceleration is the shortest, merely of about 5 ms. However, there indeed exists a critical influence of the position of the different obstacles on the flame of the explosion, though the symmetric obstacles with different lengths of flame source in the flame acceleration process turn to be quite different. For example, the obstacles near the ignition source are mainly induced by the turbulence, whereas the role of obstacles away from the ignition source should be mainly to enhance the turbulence. What is more, on the condition when the multiple symmetrical obstacles are installed, the flame would have to experience lots of times of acceleration, which can significantly increase the propagation velocity of the flame and the explosion over-pressure.