Numerical Simulation for Erosion of Helium Stratified Layer Under Effect of Vertical Air Jet

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, SETH-2 project is initiated by OECD. In the frame of SETH-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, which 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 ST1_7_2 experiment, but the effect is not significant.