瑞利数对竖直恒温面处自然对流边界层不稳定性的影响  

Effect of Rayleigh number on the instability of natural convection boundary layer at isothermal vertical surface

作　　者：王春雨 刘泽勤[1,2,3] 刘聪聪 赵鹏鹏 WANG Chunyu;LIU Zeqin;LIU Congcong;ZHAO Pengpeng(School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, China;Refrigeration Engineering Research Center of Ministry of Education, Tianjin University of Commerce, Tianjin 300134, China;Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China;School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, China)

机构地区：[1]天津商业大学机械工程学院,天津300134 [2]天津商业大学冷冻冷藏技术教育部工程研究中心,天津300134 [3]天津商业大学天津市制冷技术重点实验室,天津300134 [4]扬州大学水利与能源动力工程学院,江苏扬州225009

出　　处：《合肥工业大学学报（自然科学版）》2022年第5期602-609,共8页Journal of Hefei University of Technology：Natural Science

基　　金：国家自然科学基金资助项目(11602215);江苏省自然科学基金资助项目(BK20160453)。

摘　　要：文章采用ANSYS FLUENT软件模拟竖直恒温面处的自然对流现象,探究瑞利数Ra对自然对流边界层不稳定性的影响。该次模拟选用7种不同Ra,其变化范围为5.31×10^(8)~5.31×10^(9),在模型中加入形式为T=2A(Rand(0,1)-0.5)的随机式扰动和形式为T=Asin(2πf_(c)t)的正弦式扰动,对比在不同Ra和扰动形式下自然对流边界层的状态。模拟结果表明:在无扰动、随机式扰动和正弦式扰动状态下,随着Ra增大,竖直恒温壁面处的自然对流热边界层厚度均减小;在随机式扰动和正弦式扰动下,竖直恒温面处的自然对流热边界层沿竖直方向存在振荡,且相比于随机式扰动,正弦式扰动下的热边界层的震荡幅度更大;Ra在5.31×10^(8)~5.31×10^(9)的范围内,自然对流边界层的特征频率与Ra间的耦合公式为f_(c)=0.226Ra^(0.641)。The natural convection on the isothermal vertical surface is simulated by using ANSYS FLUENT software,and the influence of Rayleigh number Ra on the instability of natural convection boundary layer is explored.Seven kinds of Ra are selected in this simulation,the range of which is 5.31×10^(8)-5.31×10^(9).The random disturbance in the form of T=2A(Rand(0,1)-0.5)and the sinusoidal disturbance in the form of T=Asin(2πf_(c)t)are added to the model to compare the state of natural convection boundary layer under different Ra and disturbance forms.The simulation results show that the thickness of the natural convective thermal boundary layer at the isothermal vertical wall decreases with the increase of Ra under the conditions of no disturbance,random disturbance and sinusoidal disturbance.Under random and sinusoidal disturbances,the natural convective thermal boundary layer oscillates along the vertical direction,and the oscillation amplitude of the thermal boundary layer under sinusoidal disturbance is larger than that under random disturbance.The coupling formula between the characteristic frequency of the natural convection boundary layer and Ra is f_(c)=0.226Ra^(0.641) in the range of 5.31×10^(8) to 5.31×10^(9).

关 键 词：自然对流 瑞利数 边界层不稳定性 热边界层 特征频率 

分 类 号：TK124[动力工程及工程热物理—工程热物理]