Modeling and analysis of the spread characteristics of cryogenic hydrogen vapor cloud under different atmospheric boundary layers

Liquid hydrogen leakage and diffusion accidents pose serious threats to the safety of personnel and equipment. In the present work, three-dimensional CFD models for liquid hydrogen spills in unstable, neutral and stable atmospheric boundary layers are developed, and the effects of atmospheric boundary layer on prediction accuracy is validated. Spread characteristics of hydrogen vapor cloud under different atmospheric boundary layers are then numerically analyzed. Modeling the stability of atmospheric boundary layer can improve the accuracy and reliability of the prediction results for liquid hydrogen spills. Wind velocity and its gradient, as well as the vertical distribution of air temperature, act upon the spread characteristics of hydrogen vapor cloud. The unstable atmospheric boundary layer could promote the upward movement and the expansion of hydrogen vapor cloud to some extent. The stable atmospheric boundary layer promotes the vertical spread process in early stage, while presents hindering effects as the spill continues. Cloud heights at the end of the spill are respectively 48.6 m, 45.5 m and 30.2 m, under the unstable, neutral, and stable atmospheric boundary layers. In addition, wind flow in stable atmospheric boundary layer has obvious dragging effect on the lateral edge of hydrogen vapor cloud.