Study on the hydrogen leakage diffusion behavior by obstacles in confined spaces

•The impact of Q1-Turbulent Flow obstacle model on hydrogen leakage and diffusion is more serious than that of Q2-Laminar Flow, the gas in the upper part of the model is easier to accumulate, the hydrogen concentration is higher, and it takes longer to finally reach a steady state, the main reason is that the obstacle will make the injected The hydrogen deflects in the vertical direction, resulting in a loss of kinetic energy, an increase in its hydrogen concentration, a decrease in diffusion efficiency, and a delay in the process of reaching the average value.•In the ejection process of the Q1-Turbulent Flow obstacle model, when t = 0.3 s, the gas cloud just touches the obstacle and initially spreads along the obstacle. As the hydrogen leaks continuously, a large amount of gas comes into contact with the obstacle. At t = 0.5 s, the obstacle begins to block the normal diffusion of the leaked hydrogen. The initial kinetic energy loss is caused by the buoyancy and the obstruction of the obstacle, and the movement direction of the hydrogen changes. When t = 0.8 s, due to the blocking effect of the wall of the obstacle, the accumulation and eddy current areas are generated. When t = 1 s, the area of the eddy current area further increases, and the degree of danger at this time is obviously higher than before, and accidents such as suffocation and explosion are very prone to occur.•The hydrogen diffusion range of the rectangular leakage port is wider, the diffusion speed is faster, and the initial kinetic energy of the injection port is relatively large, which makes it easy to exceed the lower limit of hydrogen flammability. In this paper, a combination of experimental and numerical simulation is used to investigate the effects of obstacles and leakage hole shapes on the leakage diffusion pattern and hydrogen concentration. A small-size cubic geometry model of 0.47 m × 0.33 m × 0.20 m is used to calculate the concentration of the leakage model in the confined environment. The results show that the influence of the Q1-Turbulent Flow obstacle model on hydrogen leakage and diffusion is more serious than that of the Q2-Laminar Flow, the gas in the upper part of the model is easier to accumulate, the hydrogen concentration is higher, and it takes longer to finally reach a stable state. Rectangular leakage holes have a larger hydrogen diffusion range, faster diffusion rate, higher initial kinetic energy, and are more likely to exceed the lower flammability limit of h