摘要为找到提高或降低自然对流换热强度的方法，解决工程中遇到的一些换热问题，研究 了一个方形空腔内含有固体方块，水平壁绝热，竖直壁恒温但存在温差的自然对流换热问 题。在方块占据的体积分数保持恒定的情况下把方块均匀细分，改变块的数量、瑞利数、 长宽比、边界条件等参数用 FLUENT 软件进行数值模拟，观察它们对方腔内流体流动与换 热的影响。获得的结果表明，在中、低 Ra 数下，块的细分数量增加会显著降低流动和传 热的强度，高 Ra 数下，块的细分对传热没有明显影响；长宽比由小变大时，在低 Ra 数下 Nu 数小幅度增大，在中 Ra 数下 Nu 先增大后减小，在高 Ra 数下 Nu 数没有明显变化；将 上壁条件变为恒温热壁，可以提高传热强度。80198

毕业论文关键词 自然对流换热 封闭方腔 块的细分 数值模拟

毕 业 设 计 说 明 书 外 文 摘 要

Title Numerical simulation of convective heat transfer in a closed system with square column

Abstract In order to solve some heat transfer problems encountered in engineering,the method of raising or lowering the intensity of natural convection heat transfer is needed。a numerical study is carried out on thermal natural convection in a square cavity with adiabatic horizontal walls,thermally active vertical walls and containing blocks。 Block segmentation in the case where the volume occupied by the fluid is maintained constant。The governing parameters are Number of blocks

，the Rayleigh number，ratio of length to width and boundary condition。The numerical simulation was carried out by FLUENT software,The effects of these parameters on the flow and heat transfer of fluid were observed。The results obtained indicate that the heat transfer and the flow intensity could be significantly reduced by increasing the number of the blocks at low and moderate of the Rayleigh number。 At high values of the Rayleigh number,the subpision of the solid blocks does not lead to any practical effect on the heat transfer。At low of the Rayleigh number， the amount of Nu increases very little When the ratio of length to width increases。 At moderate of the Rayleigh number，The heat transfer intensity increases first and then decreases。At high values of the Rayleigh number,Nu of values has no obvious change。 It can increase the heat transfer intensity by Changing the boundary condition of the top wall surface is constant temperature hot wall。

Keywords Natural convection heat transfer Closed square cavity Subpision of a block numerical simulation

本科毕业设计说明书 第 I 页

目 次

1  绪论 1

1。1  前言 1

1。2  国内外研究现状 1

1。3  本文的研究内容 2

2  问题描述及物理模型 3

2。1  原理 3

2。 2  物理模型 4

2。3 FLUENT 求解设置 4

2。4  模拟的验证 5

3  块的均匀细分模拟试验 7

3。1  块的细分结果与分析 7

3。2  不同边界条件的影响 10

4  不同长宽比的模拟试验