旋转管道内对流换热特性以及开口端效应的研究

【作者】 方勇军；

【导师】 章本照；

【作者基本信息】 浙江大学 ， 流体力学， 2003， 硕士

【摘要】 旋转曲线管道系统在自然界和工程应用中随处可见，作为一个典型的物理模型，也是流体力学领域的基本问题之一，对曲线管道内流动的研究始终贯穿着流体力学这一古老学科的发展历程。理论方法和实验方法是自然科学研究基本方法，在旋转弯曲管道这一领域内常用的理论研究方法是近似理论分析和数值模拟，如摄动法就是这领域内基本的理论研究手段之一。纵观一个世纪以来有关曲线管道内流动的研究成果，本文采用了一种具有广阔应用前景的多参数旋转螺旋管道内流动模型，根据张量分析推导了旋转螺旋直角较坐标系和旋转螺旋极坐标系下流体运动的连续性方程和动量方程。然后采用数值计算方法(控制体积法)研究了绕任意轴旋转的圆形管道内的对流换热特性及流动结构，结果表明绕任意轴旋转管道内的对流换热特性主要由Re(雷诺数)，Ro(Rossby砂数)，Pr(普朗特数)数，和α(旋转轴与管道轴线的夹角)四个参数决定。文中分析了在不同α情况下流场结构、摩擦系数比、温度场与管道Nu数比率随Re数和Ro数的变化规律，为工程实际应用提供了理论依据。本文所做的另一个工作就是利用数值计算方法对三种旋转矩形截面(η=1，η＞1η＜1)单参数弯曲管道内的入口流动进行了研究，分析了在离心力和柯氏力共同作用下各流动参数和管道几何参数(如曲率，Dean数等)对轴向主流、轴向流动到充分发展流所需的入口长度、二次流动形成和发展、摩擦系数比等的影响。通过计算机数值模拟，得到了大量的数据和图形，在对其进行了整理和分析后得出一些结论，并将之与已有文献的实验研究结果和数值计算结果进行了比较，结果基本上一致。更多还原

【Abstract】 We can see the rotating curved pipes everywhere in the nature and engineering application. As a typical physical model and one of the basic problems in the field of fluid mechanics, the study of the fluid flow in curved pipes is through out the history of fluid mechanics. Scientists have taken interests in flow structure in curved pipes since the middle of the nineteenth century.Theoretic method and experimental method are the main methods in the study of natural science. The commonly used theoretic research methods are approximately theoretical analysis and numerical discretization techniques in the field of rotating curved pipes. Such as perturbation method is one of the most used theoretic methods in this field. By completely analyzing the references, we take advantage of the flow model of rotating curved pipes with multi parameters, which has widely application future, to study the entrance flow in. Using tension analysis, we present the continuity equation and momentum equations in a rotating helical right angle coordinate system and a rotating helical polar coordinate system. Then employing the numerical simulation (control volume method), we study the heat transfer and flow structure in the curved pipe which is rotating around any axis. The results show that heat transfer in curved pipe rotating around any axis is mainly effected by the four following parameters: Re (Reno number), Ro ( Rossby number), Pr(Prandtl number) , and a (the angle between rotating axis and pipe axis) . We discuss both the effects of different governing parameter a on the friction factor and flow structure and the effects of different Re and Ro numbers on Nu number. These provide the theoretic basis for the engineering application.What’s more, we numerical study the entrance flow in rotating curved pipes of different cross section (η= 1, η>1η<1). We study the effects of all kinds of flow parameters and pipe parameters (Such as curvature, Dean number, Centrifugal force and Coriolis force) on axial main flow, the distance required for the flow to become fully developed, the develop of secondary flow and friction factor.By using the method of numerical simulation, we get large amount of data and graphics. After analysis we reach some conclusions. They are in good agreement with the results of other authors.更多还原