臺灣博碩士論文加值系統

流場控制一直是空氣動力學領域學者的研究重點，因為透過流場控制可以改善許多相關的流場問題，像是翼尖渦漩結構、BVI噪音等問題。而流場控制所使用的方法不斷的推陳出新，目前所採用的基本上可分為主動式及被動式控制兩類，其差異在於有無使用任何輔助動力。本文中所使用壓電薄膜來激擾流場的方法，即屬於主動式控制;而翼尖形狀的改變，則是屬於被動式控制方法。

本研究之對象為NACA0015的三維機翼模型，在使用激擾方法時，擺膜是被安置在不同的位置上，繼而在不同的攻角下，以不同波形和頻率的訊號來驅動。本研究的目的是在評估機翼處於失速前及嚴重失速時，擺膜激擾及翼尖形狀改變這二種控制方法對改善翼尖渦漩結構的成效，同時也一並瞭解該種方法對升阻力的影響程度。流場觀察以及熱線測速儀與平衡儀之量測結果將是用來建立評估成效的依據。最佳的控制參數結論將被進一步運用到搖控直昇機上，以嘗試降低旋翼的BVI噪音。

由實驗結果得知，翼尖形狀改變中的擋板翼最能有效減少環流強度，其次則是擺膜(x/c=0.3)以56Hz的方波來激擾時。在降低直昇機所產生的BVI噪音上，卻是以擺膜在x/c=0.3處以56Hz方波來激擾時最為有效，翼尖形狀改變中的次翼效果則較差。至於在使用控制方法的同時，翼尖形狀的改變雖對升力的增加亦有幫助，但阻力也隨之增加;而激擾法則對升力與阻力皆無明顯的影響。

Flow control has always been an important research topic for the aerodynamicists, because through its use, a lot of related flow problems can be resolved, such as the break-up of the tip vortex, BVI noise, etc. The methods used for flow control develop quite rapidly, and can be basically classified into two main categories, i.e., active or passive control. Their main difference lies in the use of auxiliary power. The active control schemes applied here is the use of piezoelectric film to excite the flow field. Whereas the wing tip modification is considered a passive control scheme.
The objective of this research is to study the effectiveness of different control schemes on the structural alteration of a tip vortex originated from a three-dimensional, NACA 0015 wing model under pre- and post-stall conditions. The consequences of those control schemes on the aerodynamic performance are also evaluated. As the excitation method was concerned, bimorph made of piezoelectric film was mounted on different locations at the upper surface of the model wing under different angles of attack, and was driven with signals of different waveforms and frequencies. The assessment of success was based upon the results from the laser sheet flow visualization and measurements using hot wire anemometry and force balance. The findings on optimal control parameters were then applied to a remote-controlled helicopter model in an attempt for BVI noise reduction.
Based on the results from the experiment, the end-plate tip is the most effective one in circulation reduction, followed by the bimorph excited using 56Hz square wave. However, when BVI noise reduction is concerned, bimorph turns out to be the best candidate, better than sub-wing tip. As the issue turns to the aerodynamic performance, bimorph doesn’t cause any noticeable change in either lift or drag. But on the contrary, the change of wing-tip configuration promotes both lift and drag.

中文摘要 ……………………………………………………………… Ⅰ
英文摘要 ……………………………………………………………… Ⅱ
誌謝 ……………………………………………………………… Ⅳ
目錄 ……………………………………………………………… Ⅴ
表目錄 ……………………………………………………………… Ⅷ
圖目錄 ……………………………………………………………… Ⅸ
符號表 ……………………………………………………………… XVI



一、 緒論………………………………………………………… 1
1.1 前言………………………………………………………… 1
1.2 文獻回顧…………………………………………………… 2
1.2.1 翼尖渦漩(Tip Vortex)……………………………………… 2
1.2.2 BVI 噪音…………………………………………………… 3
1.3 研究方法及構想…………………………………………… 10
1.3.1 擺膜的激擾………………………………………………… 10
1.3.2 翼尖形狀的改變…………………………………………… 10

二、 實驗設備…………………………………………………… 11
2.1 低速風洞…………………………………………………… 11
2.2 搖控直升機………………………………………………… 12
2.3 滑環……………………………………………………… 13
2.4 搖控直升機測試區……………………………………… 13
2.5 機翼模型…………………………………………………… 14
2.6 熱線測速儀………………………………………………… 14
2.6.1 感測原理…………………………………………………… 15
2.7 皮托靜壓管與差壓計……………………………………… 17
2.8 壓電薄膜…………………………………………………… 18
2.8.1 PVDF壓電材料特性簡介………………………………… 18
2.8.2 擺膜的結合………………………………………………… 19
2.9 20MHz訊號產生器……………………………………… 21
2.10 資料擷取系統……………………………………………… 22
2.10.1 A/D卡………………………………………………………… 22
2.10.2 低通濾波器Low Pass Filter）…………………………… 22
2.10.3 Sample and Hold Circuit（SHC）…………………………… 23
2.11 平衡儀（Aerodynamic Balances）…………………………23
2.12 流場觀察設備……………………………………………… 24
2.12.1 煙霧產生器………………………………………………… 24
2.12.2 氬雷射……………………………………………………… 24
2.13 噪音量測設備……………………………………………… 25
2.13.1 麥克風……………………………………………………… 25
2.14 點膠系統…………………………………………………… 26

三、 實驗前之準備工作及規劃………………………………… 28
3.1 熱線測速儀校正…………………………………………… 28
3.2 風洞品質測試……………………………………………… 30
3.3 不確定度(Uncertainty)評估………………………………. 33
3.4 三維機翼升力曲線………………………………………… 35
3.5 流場特徵頻率的量測……………………………………… 36
3.6 擺膜安裝的位置…………………………………………… 38
3.7 翼尖形狀改變……………………………………………… 39
3.8 擺膜的驅動………………………………………………… 41
3.9 激擾頻率的決定…………………………………………… 41
3.10 實驗規劃…………………………………………………… 45
3.10.1 實驗條件…………………………………………………… 45
3.10.2 量測的位置………………………………………………… 46
3.11 實驗資料擷取流程………………………………………… 50

四、 結果與討論………………………………………………… 54
4.1 流場觀察與流場量測的比對……………………………… 54
4.2 基準機翼之流場觀察……………………………………… 55
4.3 擺膜激擾下之流場觀察…………………………………… 59
4.3.1 攻角為13度下之擺膜激擾流場觀察……………………… 59
4.3.2 攻角為24度下之擺膜激擾流場觀察……………………… 59
4.4 翼尖形狀改變之流場觀察………………………………… 63
4.4.1 攻角13度下翼尖形狀改變之流場觀察…………………… 63
4.4.2 攻角24度下翼尖形狀改變之流場觀察…………………… 65
4.5 擺膜激擾下之流場量測…………………………………… 67
4.5.1 攻角13度下之流場量測與頻譜分析……………………… 67
4.5.2 攻角24度下之流場量測與頻譜分析……………………… 67
4.6 由渦漩速度及環流強度比較控制之成效………………… 72
4.6.1 主動式控制………………………………………………… 72
4.6.2 被動式控制………………………………………………… 86
4.7 主動式與被動式控制對升力與阻力之影響……………… 94
4.7.1 主動式控制對升力與阻力之影響………………………… 94
4.7.2 被動式控制對升力與阻力之影響………………………… 94
4.8 主動式與被動式控制對BVI噪音之影響…………………… 95
4.8.1 主動式控制下之麥克風頻譜分析……………………… 95
4.8.2 被動式控制下之麥克風頻譜分析………………………… 99

五、 結論………………………………………………………… 103
5.1 結論……………………………………………………… 103
5.2 建議與未來展望…………………………………………… 104
參考文獻…………………………………………………… 105
自傳………………………………………………………… 107

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