The quenching and attenuation of hydrogen-air detonation after passing across capillaries

Hydrogen is considered as the cleanest fuel with a wide range of applications. One of the most important safety guarantees in hydrogen storage and transportation systems is the optimal design and reasonable selection of hydrogen detonation flame arrester elements. The present study is aimed at investigating the quenching and attenuation characteristics of hydrogen-air detonation after passing across different capillary assemblies. Various combinations of capillaries with different inner diameters (0.5-2.0 mm), lengths (2-200 mm) and numbers (1-13) are considered. Three propagation regimes are observed with the initial pressure and capillary assembly size, i.e., detonation quenching, propagation with a further velocity decaying following a long distance of subsonic low-velocity deflagration, and detonation re-initiation. The dependency of the maximum quenching pressure on capillary assembly size is presented. Experimental results also indicate that capillary diameter plays the most crucial role compared with capillary length and number. Detonation re-initiation is prone to occur when quenching fails. The re-initiation distance is not closely related to the capillary assembly size.