Investigation of the stoichiometric hydrogen-air detonation evolution in T-shaped pipeline

This propagation behavior of irregular detonation waves in a T-shaped pipeline filled with stoichiometric hydrogen-air mixtures is investigated, and the effects of initial pressure (21–100 kPa) and inlet section length (0.3–0.8 m) on re-initiation in the bifurcated structure were explored. Experimental results reveal that detonation waves attenuate at the bifurcation. Based on the rhoCentralFoam solver, this study focuses on the evolution of detonation failure and re-initiation processes in a two-dimensional T-shaped pipe. The results show that the failure detonation wave after diffraction will re-initiate due to shock waves and localized explosion interactions, with the subsequent sustained development and stabilization of the detonation wave by the transverse wave. Under conditions of the low initial pressure and high inlet pipe aspect ratio, the re-initiation relies on the interaction of reflected shock waves and localized explosions; under the reverse conditions, the re-initiation can occur directly by the collisions of diffracted shock waves and reflective shock waves. As the pressure rises, the vertical locations of the reflected points decrease, and the shortening can be up to 56 % compared to the same reflection. As the inlet length grows, stable detonation is delayed, yet re-initiation happens earlier. The length increase keeps the detonation recovery time nearly constant, expands the distance between the local explosion point and the reflected point, even to over five times, thus accumulating sufficient energy for re-initiation. These findings will enhance the understanding of hydrogen-air detonation propagation in bifurcated pipes and provide references for pipeline transportation safety schemes.