基于格子玻尔兹曼-元胞自动机模型的固空凝固相变模拟  

Simulation of Air Solidification Phase Transformation Based on Lattice Boltzmann and Cellular Automaton Model

作　　者：戴闻骁 郑晓红[1,2] 梁文清[1] 钱华[1] 雷刚 疏志勇 DAI Wenxiao;ZHENG Xiaohong;LIANG Wenqing;QIAN Hua;LEI Gang;SHU Zhiyong(School of Energy and Environment,Southeast University,Nanjing 210096,Jiangsu,China;Sate Key Lab of Technology Space Cryogenic Propellants-SEU Research Center,Nanjing 210096,Jiangsu,China;State Key Laboratory of Technologies in Space Cryogenic Propellants,Beijing 100028,China)

机构地区：[1]东南大学能源与环境学院,江苏南京210096 [2]东南大学航天低温推进剂国家重点实验室合作基地,江苏南京210096 [3]航天低温推进剂国家重点实验室,北京100028

出　　处：《制冷技术》2024年第2期11-17,37,共8页Chinese Journal of Refrigeration Technology

基　　金：国家自然科学基金(No.51676213);国家重点实验室基金课题(No.SKLTSCP1713)。

摘　　要：为研究液氢中固态空气(固空)在流场中的凝固过程,本文将空气视为氮氧混合物,采用格子玻尔兹曼-元胞自动机(LBM-CA)方法模拟固空晶体在强迫对流下枝晶生长过程及其晶体中氮氧浓度分布。研究发现:流场对枝晶形貌的影响表现在迎流侧与背流侧枝晶生长速度不平衡。上游的凝固潜热与析出溶质随流场在下游积聚,上下游浓度场与温度场有较大区别,导致迎流侧枝晶生长得到促进背流侧受到抑制。随着流速的增大,生长不对称性更明显,且富氧区氧浓度升高。当流速增加到0.05 m/s时,富氧区浓度达到23.48%,液氢系统爆炸风险增大。随着过冷度增大,流场导致的固空晶体形貌不对称性被削弱。在多晶粒共同结晶时,中心晶粒生长受明显抑制,且氧峰值浓度及富氧区面积较单晶粒生长时有明显提高。In order to study the solidification process of solid-air in liquid hydrogen in the flow field,the air is regarded as a nitrogen-oxygen mixture and the Lattice Boltzmann Method-Cellular Automaton(LBM-CA)method is used to simulate the dendrite growth of solid-air crystals under forced convection and the distribution of nitrogen and oxygen in the crystals.The results show that the influence of the flow field on the dendrite morphology is manifested in the imbalance of the growth rate of the dendrites on the upstream side and the downstream side.The upstream latent heat of solidification and the rejected solutes accumulate in the downstream with the flow field,which leads to the promotion of dendritic growth on the upstream and the suppression on the downstream.The growth asymmetry is more obvious and the oxygen concentration in the oxygen-rich zone increases with the increase of the flow velocity.When the flow velocity increases to 0.05 m/s,the concentration in the oxygen-rich zone reaches 23.48%which results the explosion risk of the liquid hydrogen system increases.As the subcooling increases,the asymmetry of the solid crystal is weakened.The growth of the central grain is significantly inhibited when multiple crystal grains are crystallized and the peak oxygen concentration and the area of the oxygen-enriched zone are significantly increased compared with single crystal grain growth.

关 键 词：格子玻尔兹曼-元胞自动机 固态空气 液氢 氧浓度分布 

分 类 号：TB611[一般工业技术—制冷工程] TK124[动力工程及工程热物理—工程热物理]