摘要封闭腔体内的自然对流换热问题在工程实际的问题中有着广泛的应用背景，例如，建筑物之间隔热、核能反应堆安全设计、微型电子设备的冷却等等。因而，封闭腔体内的自然对流换热问题日益得到广泛的注意。众多的国内、外学者对这个问题进行了大量的实验研究和数值分析。在不同的边界条件和Ra数下，会对自然对流造成不同的影响。论文通过建立了二维的封闭腔体模型，系统的分析不同边界条件及不同Ra数条件下，揭示了自然对流传热的情况，并建立了Ra数与Nu数之间的关系。 论文从基础传热入手，对对流换热进行了详细的分析，通过流体基本方程和传热基本方程对自然对流的数学模型进行了理论分析，并结合 Ra 数的参数特性建立自然对流的基本流动和传热方程。论文采用市面常见的商业软件 FLUENT进行数值模拟，进一步展现自然对流传热的情况。 论文通过建立封闭放枪模型，对比不同长宽比、不同温度、不同温度差、不同Ra 数等不同条件下的自然对流情况，并通过数值模拟进一步计算不同情况下的温度场、速度场等。并最终数值拟合出 Ra数与Nu数的关系图，从而给出 Ra数与Nu数之间的数学表达式。 61039
毕业论文关键词 自然对流 FLUENT数值模拟 二维封闭方腔 Ra瑞利数
Title Numerical Simulation of Natural Convection In Closed Cavity
Abstract Researches of Natural convection in closed cavity have great potentiality in nowadays engineering problems. For examples, insulation between buildings, security design in nuclear reactors, cooling down for micro electrical equipment, etc. Therefore, the problem of Natural convection in closed cavity becoming more and more important. Lots of researchers did plenty of experiments and numerical analysis. In different boundary conditions or different Ra number, there be different affects to Natural convection. This article use the 2-D model of closed cavity, analysis the different boundary conditions and Ra numbers, show the result of Natural convection, and also give the equation between Ra number and Nu number. Article starts from foundation of heat transfer and mass transfer, use the equation of heat and mass transfer to analysis the mathematical model of Natural convection, consider Ra number and give out the equation for natural convection. Article uses “FLUENT”, a commercial software, to help making numerical simulation, and shows the result of natural convection in a more specific way. Article builds several model including, different ratio of length and width, different boundary conditions, different Ra number, and use numerical simulation method to show the situation of temperature and velocity in Natural convection. And also get the graphic between Ra number and Nu number, in order to give out the equation between Ra number and Nu number.
Key words Natural convection FLUENT numerical simulation closed cavity Ra number
1 绪论1
1.1 计算传热、传质概述1
1.2 封闭腔体内自然对流问题及国内外研究状况1
1.3 数值计算方法2
1.4 FLUENT 软件介绍5
1.5 小结5
1.6 本文主要工作6
2 对流换热的理论分析7
2.1 导热概述7
2.2 对流换热理论8
2.3 自然对流换热10
2.4 小结12
3 不同长宽比对自然对流换热的影响13
3.1 FLUENT 模型的建立13
3.2 模型的参数设置及计算14
3.3 计算结果及分析16
3.4 小结20
4 不同边界条件对自然对流的影响21 FLUENT封闭腔体内自然对流的数值模拟:http://www.751com.cn/zidonghua/lunwen_66645.html