螺旋管内水和蒸汽局部传热特性研究  

Analysis of local heat transfer characteristics of water and steam in helically-coiled tube

作　　者：朱宏晔[1] 杨星团[1] 居怀明[1] 姜胜耀[1] 

机构地区：[1]清华大学核能与新能源技术设计研究院,北京100084

出　　处：《热科学与技术》2012年第1期27-33,共7页Journal of Thermal Science and Technology

基　　金：教育部博士学科点专项科研基金资助项目(20100002120036);国家重大科技专项经费资助项目(ZX06901)

摘　　要：以高温气冷堆蒸发器为背景,采用FLUENT软件模拟了单相水和蒸汽在不同尺寸螺旋管内部的流动和传热过程,研究了壁面局部传热特性。计算结果表明,远离螺旋中心线一侧局部传热较强而靠近螺旋中心线一侧传热较弱,壁面Nu周向分布非常不均匀。管径与螺旋直径之比是主要影响因素,当其值增大时截面温度极值点向螺旋中心线外侧移动,加剧了温度分布和Nu分布的不均匀性。在层流向湍流过渡区内,Re的增大使截面各点温度梯度均有所增加,同时也增大了Nu周向分布的不均匀程度,但在旺盛湍流区内Re对Nu分布无明显影响。壁面热边界条件形式对局部Nu周向分布没有显著影响。给出了局部Nu的估算式。CFD simulations using FLUENT software were carried out for the analysis of local heat transfer characterizes of water and steam in helically-coiled tubes with different geometries,such as tube diameter,coil diameter and pitch.Numerical results show that local Nusselt number is far from uniform along the periphery of tube wall because of the Dean eddy,which enhances the heat transfer process in the point far from the coil axis and depress that in the point near to the axis.For smaller coil diameter,the location with extremum temperature moves toward the outer side of the cross section and the temperature and Nusselt number distributions are more disuniform.Meanwhile,with the increase of Re,the difference of temperature gradient along the periphery of tube wall increase simultaneously.However,the relative Nusselt number distribution will not change with Re in fully turbulence region.It is also observed that the variation of boundary conditions of tube wall has no remarkable effects on relative Nusselt number distribution.A correlation for the computation of local Nusselt Number was presented.

关 键 词：螺旋管 数值模拟 湍流 传热系数 

分 类 号：TK124[动力工程及工程热物理—工程热物理]