CFX中湍流模型用于分析超临界水传热的适用性评价

Performance Assessment of Turbulence Models in CFX for Predicting Heat Transfer of Supercritical Water

通过两组典型实验数据,对商业软件CFX的12种湍流模型用于模拟超临界水竖直向上流动传热的性能进行评价。研究结果表明:强迫对流时,BSL代数应力模型与实验结果符合最好,但各模型间差异均不大;混合对流时,基于壁面函数的ε类型湍流模型不能模拟传热恶化趋势,自动壁面处理的ω类型湍流模型能模拟出传热恶化的趋势,但各模型预测结果和实验结果相差较大。评价结果表明近壁面的处理方式对模拟结果影响很大。此外,基于湍流普朗特数模拟湍流热流密度及未考虑密度脉动对传热的影响均是导致不能正确模拟超临界水传热行为的因素,建议对湍流模型进行改进。

Based on two sets of experimental data ,the performance of predicting heat transfer of supercritical water in a vertical tube using CFX code with 12 turbulence models was assessed .The result of BSL explicit algebraic Reynolds stress model agrees the most closely with the experimental data under forced convection ,but the differences among various turbulence models are small . However , under mixed convection condition ,εtype turbulence models with wall function can not predict heat transfer deterioration phenomenon , while ω type turbulence models with automatic wall treatment can ,but the predicted wall temperatures deviate largely from experimental results .The assessment results show that near wall treatment methods have great influence on the simulation results . The following two factors also lead to the unreasonably predicted heat transfer behavior ： Modeling turbulent heat flux with turbulent Prandtl number and neglecting density fluctuation . It is recommended that turbulence models should be improved .