论文总字数：27808字

摘 要

近年随着各类电子产品的普及应用，各类电子元器件的小型化和集成度也有了很大提高，但同时电子元器件发热量的提高也给电子产品的散热提出了更高要求，否则会影响电子器件的寿命及性能。目前电子器件的散热通常通过热沉结构以自然对流或强迫对流方式进行，自然对流更加经济可靠，而强迫对流散热效率更高。本文立足于强迫对流方式，设计了三种热沉结构，对其散热情况进行了仿真，针对仿真结果，又设计了一种散热和压降效果更优的热沉，提高了散热效率，把热源温度限制在了更低的区间。主要研究成果如下：

（1）设计了圆形、矩形和六边形三种热沉，经过CFD数值模拟发现在相同条件下，圆形热沉换热系数更高且对应的热源最高温度更低，原因在于空气通过圆形翅片时能够更充分地与其接触，且部分边缘翅片产生了小尺度的涡流。而矩形和六边形热沉更大的翅片空隙距离，导致部分空气无法更好地与散热翅片接触，散热效果不佳，但更大的翅片空隙距离弥补了其形状劣势，带来了更小的压降。

（2）结合圆形、矩形及六边形热沉的仿真结果，为了使热沉良好的散热及压降性能，设计了一种圆角矩形热沉，其圆角能将空气分流使其能充分接触散热翅片，而且其余三种热沉有更多的空气滞留在后部翅片周围与翅片换热，故圆角矩形热沉拥有了更高的换热系数，其对应的热源最高温度也更低。此外，虽单个翅片体积及表面积有所增加，导致了热沉重量的增加，但更好的空气动力外形，为圆角矩形热沉带来了更好的压降性能。由此可知，在实际应用中，圆角矩形热沉拥有更好的散热性能，能将热源温度限制在更低的区间，同时保持更低的流体阻力。

综合以上结论，我们可得知，当电子器件对热沉散热和压降性能都有较高要求时，圆角矩形热沉更适用，但当只对散热和压降当中某一种性能有要求且对热沉体积或重量有要求时也可以按需考虑圆形、矩形和六边形热沉。

关键词：热沉；换热系数；压降；数值模拟

Abstract

In recent years, the miniaturization and integration of all kinds of electronic components have been greatly improved with the popularization and application of many electronic products, but at the same time, the improvement of heat generation of electronic components also puts forward higher requirements for the heat dissipation of electronic products, otherwise it will affect the life and performance of electronic components. At present, the heat dissipation of electronic devices is usually carried out by natural convection or forced convection through heat sink. Natural convection is more economical and reliable, while forced convection has higher heat dissipation efficiency. Based on the forced convection mode, this paper designs three kinds of heat sink structures and simulates their heat dissipation. According to the simulation results, a heat sink with better  heat transfer coefficient and pressure drop effect is designed to improve the heat dissipation efficiency and limit the heat source temperature to a lower range. The main research results are as follows:

(1) Three kinds of heat sinks, circular, rectangular and hexagonal, are designed. The CFD numerical simulation shows that under the same conditions, the heat transfer coefficient of the circular heat sink is higher and the corresponding maximum temperature of the heat source is lower, because the air can contact with the circular fin more fully when passing through it, and some edge fins produce small-scale eddy current. The larger gap distance between rectangular and hexagonal heat sinks leads to the fact that part of the air can not contact the fins better and the heat dissipation effect is not good, but the larger gap distance between fins makes up for its shape disadvantage and brings smaller pressure drop.

(2) Combined with the simulation results of circular, rectangular and hexagonal heat sinks, in order to make the heat sink have good heat dissipation and pressure drop performance, a kind of rectangular heat sink with rounded corners is designed. The rounded corners can separate the air and make it fully contact with the fins. Moreover, the other three heat sinks have more air around the rear fins to exchange heat with the fins, so the rectangular heat sink with rounded corners has a higher heat transfer coefficient. The maximum temperature of the corresponding heat source is also lower. In addition, although the volume and surface area of a single fin have increased, resulting in the increase of heat sink weight, but the better aerodynamic shape brings better pressure drop performance for the round rectangle heat sink. Therefore, in practical application, the heat sink with rounded rectangle has better heat dissipation performance, which can limit the heat source temperature to a lower range and maintain a lower fluid resistance.

Based on the above conclusions, we can know that when electronic devices have higher requirements for heat dissipation and pressure drop performance, the rounded rectangle heat sink is more suitable, but when only one of the heat dissipation and pressure drop performance is required and the volume or weight of heat sink is required, the round, rectangular and hexagonal heat sink can also be considered as required.

Keywords: Heat sink; Heat transfer coefficient; Pressure drop; Numerical simulation

目 录

第一章 绪论……………………………………………………………………………………1

1.1 研究背景……………………………………………………………………………..1

1.2 国内外研究现状……………………………………………………………………..1

1.2.1 热沉材料研究………………………………………………………………..1

1.2.2 热沉制备工艺研究…………………………………………………………..3

1.2.3 热沉应用研究………………………………………………………………..4

1.3 研究意义及主要内容………………………………………………………………..8

第二章 热沉结构特点及其构建……………………………………………………………..10

2.1 热沉结构建立………..……………………………………………………………..10

2.2 热沉散热结构建模及装配…………………………………………………………11

2.3 热沉SLM制造流程…..……………………………………………………………..12

2.4 本章小结……………………………………………………………………………14

第三章 热沉结构CFD数值模拟原理及特点………………………………………………..15

3.1 ANSYS Icepak与Fluent简介…………………………………………………….15

3.2 流动传热方程………………………………………………………………………16

3.3 湍流数值模拟方法…………………………………………………………………16

3.4 微分方程数值解法…………………………………………………………………17

3.5 数值模拟步骤………………………………………………………………………19

3.6 本章小结……………………………………………………………………………20

第四章 热沉结构CFD数值模拟及结果分析………………………………………………..22

4.1 CFD模拟过程……………………………………………………………………….22

4.1.1 导入模型……………………………………………………………………22

4.1.2 模型网格划分………………………………………………………………22

4.1.3 边界条件设置………………………………………………………………23

4.1.4 计算求解设定………………………………………………………………24

4.2 模拟结果分析………………………………………………………………………25

4.2.1 换热效果对比………………………………………………………………25

4.2.2 压降效果对比………………………………………………………………28

4.3 本章小结……………………………………………………………………………29

第五章 SLM热沉结构优化…………………………………………………………………...30

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