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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 main physical mechanism of the Detonation Detonation Detonation (DDT) process, hydrogen and air mixtures were subjected to a detonation test using a square shock tube with a Shchelkin threaded tube. First of all, the pressure sensor was used to record the development of pressure wave in the tube, and the change rule of pressure wave velocity was discussed. Then, the high-speed camera was used to obtain the grain image of DDT transition, and the variation of dominant shock wave propagation velocity was analyzed. The results show that the propagation of flame experiences the phases of retarding, deflagration, detonation and detonation, strong detonation attenuation and steady detonation. The interaction between flame, dominant shock wave and reflected shock wave are the main factors affecting the DDT transition process . DDT distance was obtained by pressure-time recording method and smear method, but the turning distance obtained by the latter was more accurate.