臺灣博碩士論文加值系統

本論文對於三維自然對流流經散熱鰭片的穩態流動及其熱傳現象進行數值分析。以有限體積法 (FVM，Finite Volume Method)將Navier-Stokes方程式及能量方程離散化為代數方程組，並運用解壓力耦合方程的半隱式方法(SIMPLE，semi-implicit method for pressure- linked equation)加以迭代至收斂，進而解出其速度場，壓力場與溫度場。
　　首先單純探討基本散熱鰭片F1其熱傳遞現象及流場現象，雷利數(Rayleigh number)分別設定四種數值，普朗特數(Prandtl number)則保持為定值0.71，然後考慮具球面形狀(dimple)於散熱鰭片表面，其中不同球面形狀迎風角度，分別為30°、25°與15°，並考慮球面形狀分布與不同鰭片密度。探討上述因素對於局部紐賽數、平均紐賽數、速度場及溫度場的影響與散熱鰭片之熱傳增益效果。由本論文之結果可知，鰭片密度對於散熱效果為一重要參數。對於較大鰭片密度需搭配迎風角度15°之球面形狀散熱效果比較明顯，然而對於較小鰭片密度者則須搭配迎風角度30°與25°之球面形狀散熱效果比較顯著。

This thesis used finite volume method (FVM) to analyze steady-state flow and heat transfer in three-dimensional natural convection with heat fins. Using finite volume method discretes the Navier-Stokes equations and Energy Equation and then constructs a system of algebraic equations. It can be solved by semi-implicit method for pressure-linked equation (SIMPLE), and the solution must be iterated to convergence within each step to obtain the velocity field, pressure field, and temperature field.
　　First, this thesis discussed flow and heat transfer phenomenon simply for the basic heat fin(F1), as the Rayleigh number are set four numbers, and the Prandtl number keep a constant value as 0.71, and then for added the dimples on heat fin surfaces. On one hand this thesis considered the upwind degrees of dimples as 30°, 25°, and 15°, and on the other hand also considered the distribution of dimples and different density of heat fins. This thesis discussed the influence of above-mentioned factors on local Nusselt number, average Nusselt number, velocity field, temperature field, and the heat transfer enhancement of heat fins. The results show that different density of heat fins is an important factor. The upwind degree of dimples is 15° that has better heat dissipation ability for a higher density of heat fin. However, the upwind degrees of dimples are 30° and 25° that have better heat dissipation ability for a lower density of heat fin.

摘要 I
Abstract II
誌謝 III
目錄 IV
表目錄 VII
圖目錄 VIII
符號說明 XVI
第一章 前言 1
1-1 研究動機 1
1-2 文獻回顧 3
1-3 研究目的 7
第二章 模擬方法與幾何架構 9
2-1　原理 9
2-2　數學方程式 9
2-3　有限體積法 12
2-4　離散格式 13
2-4-1　Second Order Upwind 13
2-4-2　Least Squares Cell Based 14
2-4-3　動量方程的離散 15

2-4-4　能量方程的離散 16
2-5　流場計算 16
2-5-1　SIMPLE法 17
2-5-2　速度修正方程 17
2-5-3　壓力修正方程 19
2-5-4　計算流程 19
2-5-5　鬆弛因子 19
2-5-6　收斂條件 20
2-6　網格 20
2-7　幾何架構 20
第三章　結果與討論 28
3-1　網格獨立測試 29
3-2　本文模擬結果與參考文獻之比較 30
3-3　各形狀下，不同雷利數對散熱鰭片流場及局部紐賽數的影響 31
3-3-1　13片之基本散熱鰭片F1 31
3-3-2　13片之散熱鰭片F2、F3 33
3-3-3　13片之散熱鰭片F4 35
3-3-4　9片之散熱鰭片F5 36
3-3-5　9片與7片之散熱鰭片F6、F7 37

3-4　各幾何形狀散熱鰭片平均紐賽數的影響 38
第四章　結論與建議 41
4-1　結論 41
4-2　建議 43
參考文獻 124

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