碳纳米管阵列部分浸没在丙三醇中的润湿模拟 崔文智.docVIP

中国工程热物理学会 传热传质学 学术会议论文 编号：143536 不同热流边界条件下螺旋管内流动换热特性( 崔文智，刘晓见 (重庆大学动力工程学院，重庆 400044 )(Tel: Email: wzcui@cqu.edu.cn) 摘要：建立了螺旋管内流动换热的物理数学模型，对三种热流边界条件下螺旋管内湍流换热进行了数值模拟。：在相同Re数下，三种热流边界条件下的螺旋管内湍流换热系数是螺旋管圈内侧受热外侧绝热时最大，内外侧均匀受热时次之，外侧受热内侧绝热时最小；充分发展段的周向Nu数也呈现出以上趋势；在相同Re数时，曲率较大的螺旋管换热系数大。 关键词：非均匀热流密度；螺旋管；数值模拟；流动换热 Heat Transfer haracteristics in Helically Coiled Tube with Various Heat Flux Distributions CUI Wenzhi, Liu Xiaojian (College of Power Engineering, Chongqing University, Chongqing 400044, China ) Abstract: Physical and mathematic models of fluid flow and heat transfer in helically coiled tube are established, and numerical simulations of the turbulent heat transfer in helically coiled tube are performed under the three kinds of heat flux boundary conditions. It is found that when the same heat flux is exerted to the helically coiled tube surface, with the same Re number, the turbulent heat transfer coefficient of the tube is maximum when the inside of coiled tube is heat and the outside is insulation, followed by that when inside and outside heated evenly, while that is minimum when the inside of the tube is insulated and the outside heated; the Nu number of fully developed zone is also the same trend in the three kinds of heat flux boundary conditions; the heat transfer coefficient is larger with the same Re number when the curvature of coiled tube is smaller. Keywords: Non-uniform heat flux; Helically coiled tube; Numerical simulation; Convection heat transfer 0 前言 由于弯曲通道内的流体在离心力的作用下在流道的横截面上形成了二次环流，二次环流与主流的叠加使流体在弯管内形成螺旋运动，增强了流体的混合，从而使螺旋管的换热性能增强[1]，因此螺旋管在核动力、化工、发电和医学等领域应用广泛。 早在1902年，Williams[2]就观察到弯管流道截面上的最大轴向速度向弯管外侧的偏移，Grindley和Gibson（1908）[3]在关于螺旋管内空气粘性实验中注意到了曲率对流动的影响。此后，Eustice（1910,1911）[4]通过螺旋管内水流中注入墨水的方法证明了二次流的存在。一百年来人们关于螺旋管传热性能所做的研究已经很多，一些实验结果被总结成了实验关联式，能够很好的预测螺旋管内充分发展段的平均Nu数，例如针对螺旋管单相对流传热给出的Seban和McLaughlin计算式和Schmidt关联式等[1]。