受限空间内氢气泄漏扩散行为的数值模拟

NUMERICAL SIMULATION OF HYDROGEN LEAKAGE AND DIFFUSION BEHAVIOR IN CONFINED SPACE

氢分子是自然界中最小的分子,很容易通过管道接头、阀门等位置发生泄漏。由于氢气的易燃易爆属性,泄漏后形成的可燃气云一旦遇到火源容易演变成事故。因此,对氢气泄漏扩散行为进行研究有助于掌握氢气事故演化发展规律,对于事故预防具有重要意义。针对一个尺寸为0.47 m×0.33 m×0.20 m的立方体空间建立几何模型,采用自主研发的MPPBuoyantEpplFoam求解器对该模型内的氢气泄漏扩散行为进行了数值模拟,获得了氢气泄漏后的氢气浓度分布、扩散速度分布及流动扩散规律,通过与相关文献中的实验结果进行对比,二者吻合较好,初步验证了该求解器多组分扩散功能的准确性。研究结果表明,在受限空间内,氢气泄漏后表现出如下流动扩散规律:1)氢气从模型顶部竖直向下喷入计算域后,在周围静止空气阻滞作用和浮升力作用下,扩散速度迅速减小,流动的动量控制区变短;2)在氢气注入阶段,计算域氢气浓度分布会在浮力作用下呈现明显的分层效应,上部的氢气浓度高,下部的氢气浓度低;3)氢气停止注入后,在分子扩散作用下,计算域上下部氢气浓度差逐渐变小,并最终达到均匀混合。

Hydrogen molecule is the smallest molecule in nature,which is easy to leak through pipe joints,valves and other locations.Due to the flammable and explosive properties of hydrogen,the flammable gas cloud formed after leakage is easy to evolve into an accident once encountering a fire source.Therefore,the study of hydrogen leakage and diffusion behavior is helpful to grasp the evolution and development law of hydrogen accidents,and is of great significance for accident prevention.This paper aims at a dimension of 0.47 m×0.33 m×0.20 m cube space builds a geometric model,the independently developed MPPBuoyantEpplFoam solver was used to numerically simulate the hydrogen leakage and diffusion behavior in the model.The hydrogen concentration distribution,diffusion velocity distribution and flow diffusion laws after the hydrogen leakage were obtained.By comparing with the experimental results in relevant literature,the two are in good agreement,which preliminarily verified the accuracy of the multi-component diffusion function of the solver.The research results show that in the confined space,the following flow diffusion laws appear after hydrogen leakage:1)After hydrogen is vertically injected into the computational domain from the top of the model,the diffusion velocity decreases rapidly and the momentum control area of the flow is short under the blocking effect of the surrounding static air and the buoyancy force;2)In the hydrogen injection phase,the hydrogen concentration distribution in the computational domain will show obvious stratification effect under the buoyancy effect,with high hydrogen concentration in the upper part and low hydrogen concentration in the lower part;3)After the hydrogen injection is stopped,the hydrogen concentration difference between the upper and lower parts of the computational domain is gradually smaller under the effect of molecular diffusion,and finally achieves uniform mixing.