Effect of arc obstacles blockage ratio on detonation characteristics of hydrogen-air

In this paper, the influence of maximum blockage ratio of arc obstacles on hydrogen-air detonation characteristics is simulated and analyzed by using OpenFoam package. The results show that the arc obstacles can effectively reduce the deflagration-to-detonation transition distance and the optimal maximum blockage ratio is 0.7. As the maximum blockage ratio increases, the flame acceleration and initiation of detonation wave show 3 different regimes: (1) For small maximum blockage ratio, the flame is affected by Squish flow, resulting the velocity differences between the flame near the wall and in the center of the tube, and the tulip flame formation. The tulip flame will generate two local explosion points and the explosion points develop and merge to initiate detonation. (2) For intermediate maximum blockage ratio, under the interaction of the reflected shock wave and the obstacles, the flame is a narrow fingertip shape. The initiation of detonation wave is engendered by the development and fusion of multiple hot spots. (3) For large maximum blockage ratio, the flame is also a narrow fingertip-shaped. The detonation wave is initiated by the coupling of the flame front with the leading shock wave at the throat of the obstacle.