Study on the suppression of spontaneous flame propagation from high pressure hydrogen venting by porous media

Research on explosion suppression using porous media has been extensively conducted. However, existing studies have predominantly focused on the ignition and explosion of premixed gases such as methane and methane-hydrogen mixtures. A major challenge in hydrogen safety involves the spontaneous ignition of hydrogen resulting from leaks in high-pressure facilities. Therefore, to enhance the safety of hydrogen applications, this study investigates the influence of porous media on the propagation dynamics and suppression mechanisms of spontaneously ignited flames during high-pressure hydrogen release in pipelines. A numerical model of high-pressure hydrogen release in pipelines with porous media was developed using Ansys Fluent. The model integrates Large Eddy Simulation, the eddy dissipation concept, a 21-step hydrogen-air chemical reaction mechanism, and isotropic porous material properties. The results show that when the porous media were positioned 40 mm from the release outlet, the flame was most readily quenched. In contrast, when the media was placed at 80 mm, it achieved optimal absorption of the pressure wave, with an average pressure absorption rate of 61.3 % during the initial stage. The length of the porous media had a relatively minor influence on the suppression effectiveness. However, under identical conditions, if the media length did not reach the critical quenching distance (e.g., at 11 MPa and 80 mm location, a media length of 20 mm successfully quenched the flame, while 10 mm failed to do so), the flame could not be completely quenched. As the porosity increased from 0.427 to 0.61, the corresponding quenching distance also increased, indicating that higher porosity weakened the flame suppression capability of the porous media. Furthermore, the study established a predictive model for the quenching distance to quantify the interrelationships among various parameters.