本研究利用FLUENT計算流力軟體來模擬垂直軸風車之流場，求解三維非穩態不可壓縮紊流的Navier-Stokes方程式。
   使用NACA-ls0421以及NACA0024做為計算垂直軸風車的葉片，分別是四葉片以及三葉片，先利用Gambit繪製外型以及建構非結構網格並給定邊界條件，以及運用不同的紊流模式計算，在驗證的過程中，發現每次的時間步階大概需要疊代200次，且收斂條件需調整成較嚴格，才能把時間步階放大。
   本文裡有利用二維計算三種不同直徑的垂直軸風車，採用k-ε standard模式計算在不同尖速比下的扭力，其結果與實驗所得趨勢吻合，誤差在20%。
   結果發現，不同紊流模式所計算出的扭力值極為不同，且從原本計算二維流場到三維，所需計算時間增七倍多，不符合效率。雖說二維的數值解已與實驗值相近，但是在三維時；卻還需要改進，再找較符合的紊流模式來計算之。

This study used the commercial CFD software, FLUENT, to simulate the flow field of VAWTs. The governing equations are the two-dimensional, unsteady, incompressible, turbulent Navier-Stokes equations.
    The results show that the residual values should be set small enough to allow at least 200 iterations within a time step in order to obtain a converged solution. This is due to the highly unsteady and turbulent flow of VAWTs. The time step can be set larger to speed up the calculation if 200 iterations requirement is satisfied. 
The performance data of three small VAWTs were also measured in a low speed wind tunnel to validate the numerical results. The discrepancy between experimental and two-dimensional numerical results is about 20%. The trends of the performance curves predicted numerically match that obtained experimentally. Three-dimensional effects need to be further investigated. A two-dimensional simulation takes about 12 hours in a desk top computer with an Intel-I7 cpu. But a corresponding three-dimensional simulation takes about 8 days. Therefore, two- dimensional simulation is a good preliminary design tool.
Our study also demonstrates that different turbulence models affect the numerical results significantly. The application of turbulence models in VAWTs need to be investigated extensively.

第一章 前言	1
1.1研究動機	1
第二章 文獻回顧	6
2.1水平軸式風車	6
2.2垂直軸式風車	7
2.2.1垂直軸風車的分類	8
2.3風車氣動力與貝茲(Betz)理論	12
2.4Darrius風力機功率係數極限	18
2.5垂直軸風車各項參數	21
2.6近代實驗與模擬回顧	22
第三章 研究方法	25
3.1數學模式	27
3.1.1統御方程式	28
3.1.2標準k-ε紊流模式	28
3.1.3 RNG k-ε紊流模式	29
3.1.4 Realizable k-ε紊流模式	31
3.2殘差值	32
3.3 壓力與速度耦合-SIMPLE	33
3.4外型與邊界設定	34
3.5滑動網格	36
3.6實驗設備介紹	38
第四章 研究結果與討論	43
4.1網格獨立性	43
4.2殘差值的大小收斂比較	44
4.3不同的疊代次數	45
4.4不同的紊流模式	46
4.5不同的滑動區塊厚度	47
4.6與實驗比較的網格以及網格獨立性	49
4.7旋轉半徑0.2m的二維模擬與實驗值比較	52
4.8旋轉半徑0.3m的二維模擬與實驗值比較	53
4.8.1旋轉半徑0.3m的各個葉片的扭力係數-540rpm以及淨扭力係數	54
4.8.2旋轉半徑0.3m的a0由負扭力轉正扭力的速度向量圖_41.76度	55
4.8.3旋轉半徑0.3m的a0最高扭力值的速度向量圖_90.36度	55
4.8.4半徑0.3m的a0由正扭力值轉負扭力的速度向量圖_164.88度	56
4.8.5旋轉半徑0.3m的a0最低扭力值的速度向量圖_5.76度	56
4.9旋轉半徑0.4m的模擬與實驗值比較	57
4.10旋轉半徑0.3m的三維計算	57
第五章 總結與未來展望	61
參考文獻	63

表目錄
表1-1 民國100年台灣電力裝置系統 .................................................... 2
表1-2 台灣風能技術SWOT分析 ........................................................... 3
表1-3 水平軸式與垂直軸式風立機之主要差異性 ................................ 4
表1-4 工程分析法之比較 ........................................................................ 5
表2-1 垂直軸風車各項參數 .................................................................. 21
表2-2 文獻回顧 ...................................................................................... 23

圖目錄
圖2-1 各種水平軸式風車[6] ................................................................... 6
圖2-2 各種垂直軸式風車[6] ................................................................... 7
圖2-3 水平軸風機結構 ............................................................................ 9
圖2-4 Darrieus型風車結構 ...................................................................... 9
圖2-5 H型風車以及俯視圖 ................................................................... 10
圖2-6 Savonius型風車以及剖面圖 ....................................................... 10
圖2-7 現代垂直軸風機 .......................................................................... 11
圖2-8 一維風力機示意圖 ...................................................................... 12
圖2-9 流場速度與壓力經過轉子的變化圖 .......................................... 13
圖2-10一維風力機控制體積示意圖 ..................................................... 14
圖2-11 沿著流線之風力機的控制體積 ................................................ 15
圖2-12 、 與 的關係圖 ................................................................ 17
圖2-13 W.和.L.所繪垂直軸風車剖面圖以及其相關參數 .................... 18
圖2-14 各類風車的功率極限 ................................................................ 20
圖2-15 垂直軸風力機葉片的旋轉角度圖 ............................................ 22
圖3-1 研究方法流程圖 .......................................................................... 25
圖3-2 孫使用寬鬆收斂條件下不同的時間步階的功率值 .................. 26
圖3-3 孫使用嚴謹收斂條件下不同的疊代次數的功率值 .................. 26
圖3-4 不同計算方法對節點的劃分 ...................................................... 27
圖3-5 case1的外型與邊界設定 ............................................................. 34
圖3-6 case2的外型與邊界設定 ............................................................. 35
圖3-7 case2的前視圖..............................................................................36
圖3-8 滑動格點技術圖解示意圖 ........................................................ 377
圖3-9 風洞外觀 .................................................................................... 399
圖3-10 風洞整流段 ................................................................................ 39
圖3-11 風洞測式段 ................................................................................ 40
圖3-12 皮托管 ........................................................................................ 40
圖3-13 扭力計 ........................................................................................ 41
圖3-14 控制箱 ........................................................................................ 41
圖3-15 風洞的漸擴管 ............................................................................ 42
圖3-16 實驗用垂直風車 ........................................................................ 42
圖4-1 網格獨立性 .................................................................................. 43
圖4-2 各項殘差係數 ...................................................................... 44
圖4-3 各項殘差係數的 .................................................................. 45
圖4-4 不同的疊代次數 .......................................................................... 46
圖4-5 不同的紊流模式所得功率 .......................................................... 47
圖4-6 滑動區塊的厚度以及內外緣的定義 .......................................... 48
圖4-7 不同的滑動區塊厚度 .................................................................. 48
圖4-8 網格獨立性測試 .......................................................................... 49
圖4-9 網格示意圖 .................................................................................. 50
圖4-10 加密的局部網格放大圖 ............................................................ 50
圖4-11 三維網格圖 ................................................................................ 51
圖4-12 三維翼剖面旁的網格圖 ............................................................ 51
圖4-13 旋轉半徑0.2m的二維模擬與實驗值 ...................................... 52
圖4-14 半徑0.3m的二維模擬與實驗值 .............................................. 53
圖4-15 旋轉半徑0.3m各葉片的扭力係數 .......................................... 54
圖4-16 旋轉半徑0.3m，方位角41.76°的速度向量圖 ....................... 55
圖4-17 旋轉半徑0.3m，方位角90.36°的速度向量圖 ....................... 55
圖4-18 旋轉半徑0.3m，方位角164.88°的速度向量圖 ..................... 56
圖4-19 旋轉半徑0.3m，方位角5.76°的速度向量圖 ......................... 56
圖4-20 旋轉半徑0.4m的二維模擬與實驗值 ...................................... 57
圖4-21 以k-ε紊流模式計算三維風車，r=0.3m，ω=475rpm ............ 58
圖4-22 以RNG k-ε紊流模式計算三維風車，r=0.3m，ω=475rpm .. 59
圖4-23 以RNG k-ε紊流模式計算三維風車，r=0.3m，ω=540rpm .. 60
圖4-24 以RNG k-ε紊流模式計算三維風車，r=0.3m，ω=230rpm .. 60

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