Numerical Simulation Study on the Combustion Venting Characteristics of Cryogenic Hydrogen Flare

The flare system, serving as the terminal protection barrier for key equipment such as hydrogen liquefaction, storage, and filling, plays a vital role in emergency handling of large-scale unbalanced hydrogen releases. In this study, we established engineering physical models and three-dimensional Computational Fluid Dynamics （CFD） numerical models for the combustion and venting process of low-temperature hydrogen flares, and evaluated the effects of different venting temperature conditions on the combustion characteristics and thermal radiation distribution of the flare flames. The results show that during the venting process of low-temperature hydrogen, insufficient mixing between cold hydrogen and air makes jet flames more susceptible to environmental influences, resulting in significant changes in flame morphology and thermal radiation field distribution characteristics. As the hydrogen venting temperature approaches ambient temperature, the hydrogen density decreases while the flow velocity increases, leading to gradual decreases in flame volume, center offset distance of the thermal radiation field, and offset angle. Compared to the case of low-temperature venting （43 K）, the flame volume, center offset distance of the thermal radiation field, and offset angle decreased by 53.77%, 78.18%, and 49.75%, respectively, when the venting temperature was 293 K, indicating significantly increased hazard associated with low-temperature venting operations. This study provides guidance for the design of flare systems and the formulation of hydrogen safety control strategies.