高瑞利数下封闭腔内自然对流的数值模拟  

Numerical Simulations for Natural Convection with High Rayleigh Number in a Tall Rectangular Cavity

作　　者：阳祥 陶文铨[2] 

机构地区：[1]国家核电技术有限公司北京研发中心,北京100190 [2]西安交通大学能源与动力工程学院,西安710049

出　　处：《西安交通大学学报》2014年第5期27-31,共5页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金重点资助项目(51136004)

摘　　要：为了推广应用高瑞利数下的自然对流换热技术,有必要对自然对流流动与换热特性进行深入研究。采用不引入人工扰动的直接数值模拟方法,对发生在高宽比为4的封闭腔内的自然对流流动与换热进行了研究,分析了平均温度、平均主流速度、涡量和局部努塞尔数的分布特性。研究结果表明：从静止等温流体初始条件出发,不引入任何人工扰动自然对流可以顺利发展到湍流,节约了计算资源;即便瑞利数等于1010,自然对流的平均温度、平均主流速度、涡量和局部努赛尔数分布都具有边界层型流动和换热的特征;在普朗特数为0.71~500的范围,当封闭腔内自然对流换热出现湍流换热特征时,局部瑞利数处于10^7~10^8量级。To generalize heat transfer technology of natural convection with high Rayleigh number, it is necessary to extensively investigate the characteristics of fluid flow and heat transfer by natural convection. For a tall rectangular cavity of an aspect ratio 4, direct numerical simulations are carried out without any artificial perturbations on the flow field, and the distributions of averaged physical quantities such as temperature, mainstream velocity, vorticity and local Nusselt number are analyzed. The results show that： 1）Starting under quiescent and isothermal flow conditions, the flow can be driven to turbulence without any artificial perturbations, which saves computational resources; 2）As Rayleigh numbers up to 1010, the distributions of temperature, mainstream velocity, vorticity and local Nusselt numbers for natural convection in the tall cavity are endowed with the similar features of those in boundary-layer flow on a heated vertical plate; and 3）With Prandtl number in range of 0.71-500 and local Rayleigh number of magnitudes 107-108, heat transfer on the isothermal surfaces of tall cavity already presents the characteristics of turbulent flow.

关 键 词：封闭腔 湍流 自然对流 直接数值模拟 

分 类 号：TK124[动力工程及工程热物理—工程热物理]