A Numerical Study on Jet Release from Off-site and Mobile Hydrogen Refueling Station for Separation Distance

High-pressure hydrogen facilities are prone to jet release accidents. In the cases of immediate ignition, jet fire occurs, and delayed ignition can lead to explosion accidents. Therefore, its management is crucial to avoid leakage. In this study, the change in volume fraction of hydrogen and the flammable area around the hydrogen facility were calculated using a computational fluid dynamics model, for the cases of jet release accident in a hydrogen storage tank of off-site hydrogen refueling station and a mobile hydrogen refueling station. The leakage at the off-site hydrogen refueling station was through the opening at the top of the wall. The mobile hydrogen refueling station had hydrogen stagnated in the lower part of the wing body due to the wing body. Most of the hydrogen facilities were included in the hydrogen flammable zone after 10 s of the jet release. Further, after 30 s, the flammable distance was calculated to be approximately twice for of a mobile hydrogen refueling station as compared to a storage type hydrogen refueling station.

Observation and simulation of mountain wave trains in a tropical cyclone situation

This paper documents the observations by radar of wave trains downstream of mountains in a tropical cyclone situation. The wind disturbances associated with the wave trains together with the background strong southeasterly flow result in the occurrence of low-level wind shear as detected by the radar. So the case is not just scientifically interesting, but it also has practical application value. The wave trains can be simulated by using a computational fluid dynamics model initialized homogeneously by the upper air ascent data at the time close to that the occurrence of the wave trains. This points to the potential of using such a model in simple setup to forecast the occurrence of low-level wind shear.

Numerical simulation of multi-layer 3D concrete printing

This paper presents a computational fluid dynamics model fit for multi-layer 3D Concrete Printing. The numerical model utilizes an elasto-visco-plastic constitutive model to mimic the flow behaviour of the cementitious material. To validate the model, simulation data is compared to experimental data from 3D printed walls. The obtained results show that the numerical model can reproduce the experimental results with high accuracy and quantify the extrusion load imposed upon the layers. Such load is found to exceed the material’s yields stress in certain regions of previously printed layers, leading to layer deformation/flow. The developed and validated numerical model can assist in identifying optimal printing strategies, reducing the number of costly experimental print failures and human-process interaction. By doing so, the findings of this paper helps 3D Concrete Printing move a step closer to a truly digital fabrication process.