SST k-ω-γ模型修正及其对螺旋管内层流向湍流转捩过程的预测  

Modified SST k-ω-γModel and Prediction of Laminar to Turbulent Flow Transition in Helical Tube

作　　者：蔡昀彤 赵后剑 李晓伟[2] 苏阳 鹿一鸣 郭张鹏 刘芳 Cai Yuntong;Zhao Houjian;Li Xiaowei;Su Yang;Lu Yiming;Guo Zhangpeng;Liu Fang(School of Nuclear Science and Engineering,North China Electric Power University,Beijing,102206,China;Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing,100084,China)

机构地区：[1]华北电力大学核科学与工程学院,北京102206 [2]清华大学核能与新能源技术研究院,北京100084

出　　处：《核动力工程》2024年第6期55-62,共8页Nuclear Power Engineering

基　　金：国家重点研发计划资助项目(2022YFB1902503);国家自然科学基金面上项目(12275084)。

摘　　要：螺旋管式换热器因具有结构紧凑和换热性能好等优点,在各领域被广泛应用。区别于直管内流动,流体在螺旋管内流动时会受到离心力作用。由于离心力的存在,螺旋管内层流向湍流转捩的临界雷诺数会随着螺旋曲率的增大而增大。本文采用数值方法研究了螺旋管内层流向湍流的转捩过程,通过分析阻力系数随雷诺数的变化关系,对比剪切应力输运(SST)k-ω-γ-Re_(θ)模型和SST k-ω-γ模型模拟转捩过程的准确性,分析了不同入口湍流强度(5%、10%)对计算结果的影响。SST k-ω-γ-Re_(θ)模型对入口湍流强度较敏感,而SST k-ω-γ模型受入口湍流强度影响较小。与前人经验关系式相比,SST k-ω-γ模型模拟得到的临界雷诺数偏大。本文通过调节SST k-ω-γ模型中γ输运方程的经验系数,发现经验系数C_(TU1)对转捩起始点有较大影响,同一曲率下,临界雷诺数随C_(TU1)增大而增大。本文基于现有经验公式确定了不同曲率螺旋管(0.02、0.04、0.06、0.11)所对应的C_(TU1),并拟合得到螺旋曲率和C_(TU1)的关联式,验证了修正后SST k-ω-γ模型模拟螺旋管内层流和湍流阻力系数的准确性,比较了SST k-ω模型和修正SST k-ω-γ模型计算结果中速度、湍动能以及湍流粘度等变量的不同。Helical tube heat exchangers are widely used in various fields due to compactness and good heat transfer performance.Different from the flow in a straight pipe,the fluid will be subjected to centrifugal force when flowing in a helical tube.Due to the existence of centrifugal force,the critical Reynolds number for the transition from laminar to turbulent flow in the helical tube increases with the increasing of helical curvature ratios.In the current investigation,the transition process from laminar to turbulent flow in the helical tube is studied by numerical method.By analyzing the relationship between the resistance coefficient and Reynolds number,the accuracy of simulating the transition process by the shear stress transport(SST)k-ω-γ-Re_(θ)model and SST k-ω-γmodel is compared,and the effects of different inlet turbulence intensities(5%and 10%)on the calculation results are analyzed.The SST k-ω-γ-Re_(θ)model is more sensitive to inlet turbulent intensities,while the SST k-ω-γmodel is less affected by inlet turbulent intensities.The critical Reynolds number obtained by SST k-ω-γmodel is larger than the critical Reynolds number calculated by the empirical correlation in the literature.In this paper,by adjusting the empirical coefficient ofγtransport equation in SST k-ω-γmodel,it is found that C_(TU1) has a significant influence on the onset of the transition process.With the same helical curvature ratio,the critical Reynolds number increases with the increasing of C_(TU1).In the current investigation,based on the existing empirical formula,the C_(TU1) for different helical curvature ratios(δ=0.02,0.04,0.06,and 0.11)are determined,and the correlation between helical curvature and C_(TU1) is obtained by fitting.The accuracy of the modified SST k-ω-γmodel in simulating the laminar and turbulent friction factors in helical tubes is verified,and the differences of velocity,turbulent kinetic energy and turbulent viscosity in the calculation results of SST k-ωmodel and modified SST k-ω-γmodel are c

关 键 词：螺旋管 阻力系数 层流 湍流 转捩 

分 类 号：TK124[动力工程及工程热物理—工程热物理] TL334[动力工程及工程热物理—热能工程]