Detonation Propagation Behaviors in an Obstructed Bent Tube

The propagation behaviors of hydrogen-oxygen detonation wave in a bent tube containing an array of obstacles were experimentally investigated at different initial pressures. A straight tube with the same configuration was chosen as the control group. The bent tube was a semicircular tube with a square cross-section. The obstacles were rectangular and the blockage ratio was 40%. Through pressure monitoring and soot foil recording, the results show that the propagation process of the detonation wave between obstacles can be roughly divided into five stages, which are irregular cells, no cells, finer cells, transition zone and normal cells, respectively. Firstly, after the detonation wave in the bent tube diffracts along the obstacle, it does not decouple immediately. The detonation wave undergoes a transient failure due to the action of the rarefaction wave after a head-on impact with the bottom wall to form irregular cells. Then a planar overdriven detonation wave is formed at the outer wall and gradually expands to the inner wall. Afterwards, the overdriven detonation gradually decays into a stable detonation. However, when the initial pressure decreases gradually in the straight tube, local decoupling occurs after the detonation wave diffracts along the obstacle. This results in the formation of a no cells region on the bottom wall first, then the five stages mentioned above occur. In addition, during the stable detonation stage, the detonation cell width in the bent tube decreases gradually from the inner wall to the outer wall and is approximately linearly distributed. The cell width from the detonation database at the corresponding initial pressure is closer to that at the inner wall. The cell width in the straight tube is in good agreement with the data from the detonation database.