竖直空气射流对氦气层侵蚀行为的数值模拟

摘要

In the case of a severe accident in nuclear power plant , some amount of hydrogen will be released into the containment . In order to investigate the complex phenomena such as stratification , mixing and recombination of hydrogen , SET H-2 project is initiated by OECD .In the frame of SET H-2 project ,ST1_7_2 experiment conducted on PANDA facility used helium as substitute of hydrogen to simulate the erosion process of a hydrogen stratified layer by a vertical jet .CFD was adopted in this paper to make the numerical simulation of ST1_7_2 experiment .The effect on numerical simulation by buoyancy turbulence model and different turbulence Schmidt numbers was also analyzed .The results indicate that the numerical simulation reproduces the erosion process qualitatively ,but the erosion rate is under-predicted in numerical simulation . Fast dilution of the helium stratification layer by air jet-flow at the very beginning in numerical simulation without buoyancy turbulence model is obtained ,w hich deviates the experimental results greatly ,so the buoyancy turbulence model should be adopted in numerical simulation .Different Schmidt numbers have a little effect on the results of numerical simulation for the ST 1_7_2 experiment ,but the effect is not significant .%核电厂在严重事故时会有大量氢气释放到安全壳中，为研究氢气在安全壳内的分层、混合、复合等复杂现象，OECD发起了SET H-2项目。在SET H-2框架内，PANDA实验台架上进行的ST1＿7＿2实验利用氦气替代氢气，来模拟竖直空气射流对氢气层侵蚀的过程。本文使用C FD技术对该实验进行了数值模拟，并分析了浮升力湍流模型以及不同湍流Schmidt数对模拟结果的影响。研究结果表明：数值模拟较好地再现了实验的侵蚀过程，但射流的侵蚀速率小于实验的侵蚀速率；使用不考虑浮升力的湍流模型进行模拟的结果显示，氦气层迅速被空气射流稀释，与实验现象不符，表明在定义湍流模型时必须考虑浮升力；不同湍流Schmidt数对ST1＿7＿2实验的数值模拟结果存在一定影响，但影响不大。