Abstract:

Through the self-designed and built small experimental platform, the flame structure change, flame front dynamics and pressure evolution of methane flame propagation process were studied when the blockage rate gradient was 0, 0.05, 0.1 and 0.15 respectively. The results show that when the blockage rate gradient is 0 and 0.05, the flame front will gradually become clear after passing through the obstacles, and then the flame front will sag to the combustion zone. When the blockage rate gradient is 0.1 and 0.15, the front end of the flame is always blurred after passing through the obstacles, and then the turbulent combustion intensifies, and deflagration occurs rapidly in the whole pipeline, and there is no flame front depression phenomenon. The blockage rate gradient has a great influence on the instantaneous flame velocity, but not on the average flame velocity. With the increase of blockage rate gradient from 0 to 0.15, the maximum flame velocity increases obviously, but the average flame velocity is almost the same. In addition, the obstacle group with high blockage rate gradient is conducive to pressure accumulation. With the increase of blockage rate gradient, the peak overpressure increases regularly, and the time to reach the peak overpressure increases accordingly.

Key words: explosion, methane, obstacles, blockage rate gradient, turbulence

摘要：

通过自主设计并搭建小型实验平台，研究障碍物阻塞率梯度依次为0、0.05、0.1、0.15时，甲烷火焰传播过程的火焰结构变化、火焰前锋动力学以及压力演变。结果表明：阻塞率梯度为0和0.05的工况，经过障碍物后的火焰前锋会由模糊逐渐变得清晰，随后火焰前锋会向燃烧区凹陷；而阻塞率梯度为0.1和0.15工况的火焰在经过障碍物后，前端始终模糊，随后湍流燃烧加剧，迅速在整个管道爆燃，并无火焰前锋凹陷现象。阻塞率梯度对火焰瞬时速度影响较大，而对平均速度并无太大影响。随着阻塞率梯度从0增大到0.15，最大火焰速度会明显提升，而平均火焰速度却近似一致。此外，高阻塞率梯度的障碍物组有利于压力积聚，随着阻塞率梯度的增大，峰值超压也呈现规律性的增大，达到峰值超压所需的时间也相应延长。

关键词: 爆炸, 甲烷, 障碍物, 阻塞率梯度, 湍流