三角形棒束内铅铋湍流普朗特数模型研究

Turbulent-Prandtl-number models for liquid lead-bismuth in triangular rod bundles

为准确预测低普朗特数流体在燃料组件棒束子通道内的传热特性,需选取合适的湍流普朗特数模型。针对5种不同的湍流普朗特数模型,基于三角形棒束换热关联式,研究采用剪切应力传输(Shear Stress Transfer,SST)k-ω湍流模型,分析不同的棒束子通道结构,并与液态铅铋实验验证的换热关联式计算结果进行对比,分析不同棒径与节径比条件下各种湍流普朗特数模型的适用性。分析研究结果表明,整体湍流普朗特数模型不仅与雷诺数Re、贝克莱数Pe有关,还与节径比P/D有关;在节径比1.3~1.7范围内Kays学者提出的局部湍流普朗特数模型模拟结果与Mikityuk关系式计算值较为吻合;各种湍流普朗特数模型均有最佳的节径比适用范围。因此,相关模型能够用于不同节径比条件下三角形棒束子通道内铅铋传热特性的预测。

[Background]In order to accurately predict the heat transfer characteristics in the sub-channel of fuel assembly for the low Prandtl number fluid,it is necessary to select a suitable turbulent-Prandtl-number model.[Purpose]This study aims at the applicability of turbulent-Prandtl-number models for liquid lead-bismuth turbulence in triangular fuel rod bundles.[Methods]Based on the triangular rod bundle heat transfer correlation,the turbulent models of Shear Stress Transfer(SST)k-ωwas adopted to analyze the different rod bundle structures for five different kinds of turbulent-Prandtl-number models.The analysis results were compared with the recommended heat transfer correlation,which had been verified by experiment in the sub-channels for liquid lead-bismuth.The applicability of various turbulent-Prandtl-number models under different rod diameters and pitch diameter ratios was analyzed in details.[Results]The results show that the global turbulent-Prandtl-number model is not only related to the Reynolds number Re and Peclet number Pe,but also related to the pitch-to-diameter ratio(P/D).In the entire region of(1.3≤P/D≤1.7),simulation results of turbulent-Prandtl-number model proposed by Kays are in good agreement with the values calculated by Mikityuk equation.All sorts of turbulent-Prandtl-number models have the best P/D scope of application.[Conclusions]The related turbulent-Prandtl-number models can be used to predict the heat transfer characteristics of liquid lead-bismuth in the triangular rod bundles under different pitch diameter ratios.