爆轰火焰在管道阻火器内的传播与淬熄特性

采用数值模拟方法，研究了3种宽度(20、10、5 mm)管道内乙烯/空气预混气体的火焰加速及爆燃转爆轰(DDT)过程。研究发现，管道宽度d越小DDT发生时刻越早，但是DDT发生时的长径比却随d减小而增加。窄管道的边界层内易形成热点而引发DDT，而宽管道内更容易在管道内部引发局部爆炸形成DDT。当d =20 mm时，爆轰波以多头爆轰波传播；d =10 mm时，爆轰波呈单头旋转结构；d =5 mm时，没有出现爆轰胞格结构，只观察到较大的压力脉冲类周期出现，爆轰以1 166~1 822 m/s的速度传播，平均速度为1 380 m/s。

Theoretical analysis on deflagration to detonation transition

The process of flame acceleration and deflagration to detonation (DDT) of ethylene/air premixed gas in three widths (20 mm, 10 mm and 5 mm) channels were studied by numerical simulation. It is found that the smaller the channel width d is, the earlier DDT occurs, but the length-diameter ratio of DDT increases with the decrease of d. In the narrow channel, the DDT is easily caused by the formation of hot spots in the boundary layer. In the wide channel, it is more likely to cause local explosion inside the pipe to form DDT. When d =20 mm, the detonation wave propagates in the mode of multi-head. When d =10 mm, the detonation wave has a single head rotating structure. When d =5 mm, no cellular structure appears, and only large pressure pulse-like cycles can be observed. The detonation velocity propagates at the speed of 1 166 m/s to 1 822 m/s, and the average velocity is 1 380 m/s.