密闭空间内非均匀预混氢气泄漏爆炸过程数值模拟

To investigate the explosion behavior of hydrogen clouds with varying degrees of uniformity formed by hydrogen leakage in a confined space, a 64 L cubic chamber was designed using ANSYS Fluent software. The hydrogen leakage, standing, and explosion processes were simulated using the component transport model. The results indicate that, due to gravity, hydrogen preferentially accumulates along the upper enclosure boundary and slowly diffuses downward, leading to the formation of volume fraction gradients within the confined space. During the settling process, which lasts up to 500 s, the volume fraction gradient gradually decreases, with the maximum volume fraction difference in the space reducing from 63. 25 percentage points to 1. 37 percentage points. Ignition of hydrogen clouds with varying dispersion times reveals that the flame propagation distance of the non-uniform gas cloud differs across the three spatial dimensions. This difference gradually diminishes as the degree of uniformity increases. At equivalent time points, the case with a 150 s standing time exhibits the longest upward flame propagation distance, due to slightly fuel-rich conditions that accelerate explosive reaction kinetics. As the gas cloud uniformity increases, the average flame propagation speed in the upward, horizontal, and downward directions all increase significantly, with increases of 65. 31%, 89. 42%, and 107. 28%, respectively. The propagation speed of the uniform gas cloud explosion flame is approximately the same in all three directions. Peak explosion overpressure shows a decelerating growth trend as the standing duration increases, which can be effectively modeled by a power-function relationship. The wall temperatures of non-uniform explosion flames exhibit directional dependence, with the middle position temperature being the highest, followed by the upper position temperature, and the lowest being at the lower position. This directional disparity decreases as the mixture uniformity increases, eventually converging to a uniform temperature of 2 930 K. The results of this study can be applied to gas distribution modeling in spaces following hydrogen leakage and to explosion risk prediction, providing a valuable reference.