氢气爆燃转爆轰特性试验研究

Experimental study on characteristics of hydrogen deflagration to detonation transition

为揭示爆燃转爆轰(DDT)过程的主要物理机理,用带有Shchelkin螺纹管的方形激波管,对氢气和空气混合气进行爆轰试验。首先采用压力传感器记录压力波在管内的发展过程,探讨压力波速度的变化规律;然后借助高速照相机获得DDT转捩过程的纹影图像,分析主导激波传播速度的变化规律。结果表明,火焰传播经历缓燃、爆燃、爆燃转强爆轰、强爆轰衰减以及稳定爆轰等阶段;火焰、主导激波和反射激波间的相互作用是影响DDT转捩过程的主要因素。采用压力-时间记录法和纹影法分别得到DDT距离,但用后者所得的转捩距离更为准确。

To reveal the dominant physical mechanisms of the DDT, an experimental study on detonation properties of hydrogen air mixtures was carried out in an obstructed square channel. A Shchelkin spiral was used to accelerate the flame propagation. Firstly, data on the compression wave propagation process were obtained along the channel by pressure transducers. The variation of the front propagation velocity was discussed accordingly. Secondly, photographs of the DDT were gotten by using a high-speed digital camera. The variation of the precursor shock propagation velocity was analyzed. The experimental results show that the flame propagation undergoes several typical stages such as slow deflagration, fast deflagration, and strong detonation, and detonation attenuation, as well as steady detonation. Interaction among flame, precursor front and reflected shock waves is the main factor affecting the transition physical mechanisms of DDT. The length of DDT can be obtained by the pressure-time record method or the schlieren technique, respectively. However the transition length obtained by the schlieren method is more accurate.