基于CFD的液氢泄漏扩散防护方式特性研究

Research on Characteristics of Liquid Hydrogen Leakage Diffusion and Protection Methods Based on CFD

研究了大规模液氢泄漏过程中氢气云团的宏观扩散过程,并与美国国家航空航天局1981年液氢泄漏实验数据对比验证模型可靠性。研究了不同泄漏时间下氢气云团的扩散规律,拟合得到了液氢停止泄漏后氢云快速扩散阶段的浓度变化规律。对比研究了在泄漏口上风向设置障碍物和在泄漏口下风向设置出风口2种防护方式对液氢泄漏扩散过程的影响,并分析了扩散过程中浓度在可燃范围内氢气云团的最大扩散距离、离地高度和在大气中的持续时间3个主要参数,验证了2种方法都能够一定程度上促进氢气云团的扩散速度。在泄漏口上风向设置障碍物能够有效减小氢气云团体积,并且使氢气云团浓度下降至低于可燃浓度的时间减少15%。而在下风向设置出风口则使得氢气云团浓度下降至低于爆轰浓度的时间减少50%,并且吹风作用增加了可燃云团的离地高度,减小了云团在下风向的危险范围。

The macroscopic diffusion process of the hydrogen cloud during the large-scale liquid hydrogen leak was studied,and the reliability of the model was verified by comparing with the data of the 1981 liquid hydrogen leak experiment of the National Aeronautics and Space Administration.The diffusion law of the hydrogen cloud under different leakage times were studied,and the concentration change law of the hydrogen cloud during the rapid diffusion stage after the liquid hydrogen stops leaking was obtained by fitting.Then,the influence of the two protection methods of setting obstacles in the upper wind direction of the leak and setting the air outlet in the wind direction of the leak on the diffusion process of liquid hydrogen was obtained and analyzed.The maximum concentration of hydrogen cloud in the flammable ranges during the diffusion process.The diffusion distance,height above the ground and duration in the atmosphere were obtained and analyzed,it is found that both methods can promote the diffusion speed of hydrogen cloud to a certain extent.Setting obstacles in the wind direction above the leak can effectively reduce the volume of the hydrogen cloud and reduce the time for the hydrogen cloud concentration to drop below the combustible concentration by 15%.Setting the air outlet in the downwind direction significantly reduces the time for the hydrogen cloud concentration to drop below the detonation concentration by 50%,and the blowing effect increases the height of the combustible cloud from the ground,reducing the danger range of the cloud in the downwind direction.