臺灣博碩士論文加值系統

由於能源危機、氣候變遷、世界油價的不穩定，綠色能源中的風能再一次受到重視。其中Savonius風力機擁有噪音小、構造簡單、成本低、不受風向影響等優點，預期阻力型風力機未來將會穩定快速成長，並逐漸扮演著重要的能源角色。
本研究利用計算流體力學之數值方法模擬分析阻力型風力機之氣動力特性，再藉由改變幾何設計參數，包括重疊比、分離間距、葉片數、葉片形狀等，探討其對風力機氣動力的影響，進而提出效能較高的阻力型風力機的造型。
研究結果顯示：(1)隨著尖端速度比的增加，轉子中心處的迴流變大、變強，但葉片尖端的渦流則是變小、變弱，而造成氣動力性能下降；(2)阻力型風力機葉片間的重疊間隙，可以平衡葉片凹面的低壓，同時也縮小迴流的區域，而提升風力機的氣動力性能；(3)減少分離間距可以提升分離點的壓力，但平衡葉片凹面低壓的能力卻變弱，故改變分離間距對風力機的氣動力性能沒有幫助；(4)3葉片的阻力型風力機之扭力變化的幅度較平緩； (5)採用重疊比為0.15、Bach type的葉片形狀之阻力型風力機，在尖端速度比為1.25時有最大的輸出功率係數0.3186。

Wind energy have once again sparked the discussion of the use of green energy because of energy shortage and climate anomalies and recent price increases on the petroleum. Savonius wind turbine has the advantages of low noise, simple structure, low cost and didn’t influence by wind direction, etc. Forecasting the drag type wind turbine will gradually become the mainstream in wind power generation.
In this work, a numerical study has been carried out for analyzing the aerodynamic performance of drag type wind turbine. The study discussed about variation of aerodynamic performance of drag type wind turbine by the variation of different governing parameters, including the overlap ratio, the separation gap, the number of buckets, and the cross-section profile. Based on the above parametric analysis, this paper provides the best profile for Savonius wind turbine.
The results show that (1) as the tip speed ratio increases, the recirculating flow located at rotor center becomes larger and stronger, but the vortex near the blade tip becomes more weaken and small, which leads to the reduce in aerodynamic performance of Savonius wind turbine; (2) the overlaps of the rotor can balance the low pressure appearing on concave of blades, which will decrease recirculating region and increase aerodynamic efficiency; (3) as the separation gap decreases, the low pressure located at separation point becomes larger. This results in the lessening in ability of balancing the low pressure at concave of blades, which cannot promote aerodynamic performance; (4) the torque change in Savonius wind rotor with three blades is less than that with two blades; (5) the Savonius wind rotor with Bach-type blades and 0.15 overlap radio will have maximum power coefficient under the condition of tsr=1.25.

摘　要 I
ABSTRACT II
致謝 IV
目 錄 V
表目錄 VII
圖目錄 VIII
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 2
1.2.1 阻力型風力機之實驗相關文獻 2
1.2.2 阻力型風力機之數值模擬相關文獻 5
1.2.3 改善性能的研究文獻 7
1.3 研究目的 10
第二章 風力機基本理論 12
2.1 風能轉換系統 12
2.2 可以利用的風能 15
2.3 風力機的流速計算 16
2.4 Betz極限 17
2.5 Savonius風力機作動的原理 19
2.6 Savonius風力機的性能參數 20
2.7 阻力型風力機的幾何參數及座標系統 22
第三章 數值方法 24
3.1 基本統御方程式 24
3.2 紊流與紊流模式 25
3.2.1 紊流 25
3.2.2 紊流模式 29
3.3 數值方法 30
3.3.1 對流-擴散方程式的差分型式 31
3.3.2 壓力-速度耦合關係的處理 33
3.4 數值邊界條件 37
第四章 結果與討論 38
4.1 阻力型風力機氣動力特性之分析 38
4.1.1 阻力型風力機模型與網格建立及邊界條件設定 38
4.1.2 格點獨立 41
4.1.3 時間獨立 42
4.1.4 數值穩定性 43
4.1.5 數值模式的驗證 44
4.1.6 阻力型風力機扭力性能與葉片表面壓力分布及流場分析 45
4.1.7 尖端速度比對阻力型風力機扭力性能與流場的影響 50
4.1.8 阻力型風力機Ct、Cp分析 55
4.2 幾何參數對風力機氣動力討論 56
4.2.1 重疊比對阻力型風力機性能的影響 57
4.2.2 分離間距對阻力型風力機性能的影響 67
4.2.3 葉片數對阻力型風力機性能的影響 77
4.2.4 Bach type葉片形狀對阻力型風力機性能的影響 81
第五章 結論與建議 87
5.1 結論 87
5.2 建議 88
參考文獻 89
符號彙編 91

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