Primary Studies on Factors for Hydrogen Concentration Distribution in Containment under Severe Accidents
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摘要: 利用计算流体力学程序FLUENT和GASFLOW,采用不同的湍流模型,研究了核电站严重事故下氢气在安全壳内的传输与混合过程。计算结果表明,FLUENT中的RNG k-ε模型能够较好的模拟氢气的质量扩散,动量扩散和湍流脉动特征;FLUENT中的标准k-ε模型和GASFLOW中的k-ε模型能得到工程上可以接受的计算结果;而GASFLOW中代数模型未能较好地模拟氢气的质量扩散和动量扩散,氢气的浓度场分布与其他模型的计算结果存在较大的差别。同时,本文对混合气体中的水蒸汽浓度和气体的质量流速对安全壳内氢气浓度分布的影响进行了初步研究。研究表明,破口气体的密度和流速是影响氢气浓度场的重要因素;混合气体密度越小、流速越大,则有更大的浮力和初始动量作用于气体。湍流模型的选择和对浮力驱动的湍流射流的模拟是影响严重事故下氢气在安全壳内的分布模拟结果的重要因素。Abstract: Three factors that may affect the hydrogen concentration distribution in the containment were investigated.Calculation results by FLUENT and GASFLOW were compared.The results indicate that RNG k-ε model can obtain better results in parameter fluctuation caused by turbulence,velocity field and hydro-gen concentration field than the other models.The results calculated by algebraic model in GASFLOW are different from the other results in the simulation of mass diffusion,momentum diffusion,and parameters fluctuation.The effects of steam concentration and mass flow rate at the leakage on hydrogen concentration distribution have been also investigated.The results indicate that they are two important factors having effects on hydrogen concentration distribution.Turbulence modeling and simulation of turbulent buoyant jets and plumes,which need further study,are of importance in hydrogen concentration distribution in the containment under severe accidents.
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Key words:
- Severe accident /
- Hydrogen distribution /
- Containment
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