臺灣博碩士論文加值系統

渦漩(vortex)流場是流體力學常見中的一種基本現象，對於一有限翼展(Finite Span)之機翼端而言，因上下翼面壓力梯度的連續性變化欲在翼端上達成平衡，因此有環流現象的產生而形成翼端渦漩(Tip Vortex)，其不僅會改變翼端附近的流場結構，而且也會影響整個鄰近飛行翼面之性能及下游區域的流場穩定性。本研究中利用兩個NACA0015的翼面模型在一低速風洞中，以前後排列方式模擬前述情況。而壓電薄膜材料所製成的擺膜(Bimorph)安置在前置翼上，由不同頻率之合成訊號驅動，並改變擺膜之形狀大小以及黏貼位置。再經由熱線測速儀，量測流場速度分佈。透過結果之分析以評估壓電薄膜材料對翼端渦漩的形成以及固體表面交互作用之影響，進一步提供研究人員及工程設計者一有價值的參考資料。
由量測結果可知，以擺膜來當作激擾源對於前置翼所釋放的翼尖渦漩能夠有效減小渦漩速度結構，而擺膜安裝位置的改變會使渦漩產生偏移的效果且渦距有縮短的趨勢。在改善BVI效果方面，以複合頻率來驅動擺膜能夠使渦漩與固體表面的錯距加大，並且也能使環流強度減少。若以振動為週期來分析流場中渦漩速度變動情況來看，則以單一頻率來驅動擺膜，所造成渦漩速度隨振幅上下變動的效果最大

Vortex is a basic but important flow phenomenon in fluid dynamics. As flow passes a finite wing it will from a vortex structure at the tip due to the pressure difference between upper and lower wing surface. This tip vortex not only will affect the flowfield around the wing, but can also produce unwanted vibratory load on the downstream lifting surface and cause noise due to vortex-surface interaction, as in the case of a helicopter rotor. This so called BVI noise was mainly affected by the structure and strength of the tip vortex and the missing distance between the vortex and the surface. In this study, the situation was simulated in a table-top low-speed wind tunnel using two NACA0015 wing sections. Bimorph made from PVDF film was used as a control mean trying to influence the factors that govern the BVI noise. The size and location of bimorph, and its driving signal are the main test parameter. Their effects on the vortex-surface interaction will be evaluated through flow visualization velocity and pressure measurements .
Based on the results from the measurement, several conclusions can be drawn. Firstly as bimorph''s excitation applied the strength of vortex is reduced. Change of bimorph''s mounting locations can soothe the velocity structure of the vortex and reduce its core size . Secondly, as BVI is concerned, using compound driving signal can increase the missing distance and reduce the strength of the vortex, which will be very beneficially

中文摘要-------------------------------------------------i
英文摘要-------------------------------------------------------------------------------ii
致謝-------------------------------------------------------------------------------iii
目錄-------------------------------------------------------------------------------iv
表目錄-------------------------------------------------------------------------------vi
圖目錄-------------------------------------------------------------------------------vii
符號說明-------------------------------------------------------------------------------x
一、緒論-------------------------------------------------1
1.1 課題背景-----------------------------------------------1
1.1.1 翼尖渦漩---------------------------------------------1
1.1.2 BVI噪音-------------------------------------------2
1.2 研究構想---------------------------------------------4
二、實驗設備及方法-----------------------------------------6
2.1 實驗設備-----------------------------------------------6
2.1.1 熱線測速儀-----------------------------------------6
2.1.2 壓電薄膜（PVDF）-----------------------------------11
2.1.3 機翼模型----------------------------------------14
2.1.4 低速風洞---------- ---------------------------14
2.1.5 雷射與光頁產生系統-----------------------------15
2.1.6 煙霧產生器--------------------------------16
2.1.5 數位攝影機----------------------------------------17
2.2 實驗方法與規劃--------------------------17
2.2.1 流場觀察--------------------------------------17
2.2.2 流場量測------------------------------------------18
2.2.3 量測範圍----------------------------------------18
2.2.4 擺膜安裝位置--------------------------------------20
2.2.5 激擾頻率的決定------------------------------------21
2.2.6 重覆性實驗---------------------------------------22
2.2.7 實驗條件規劃--------------------------------------23
三、結果與討論------------------------------------------26
3.1 流場觀察結果-----------------------------------------26
3.2 擺膜激擾控制之量測結果-----------------------------29
3.2.1 單一頻率30Hz之激擾結果--------------------------29
3.2.2 其它頻率、複合頻率及改變激擾位置結果------------31
3.2.3 改變前置翼高度量測結果------------------------------32
3.2.4 改變擺膜大小後的量測結果------------------------------34
3.3 擺膜激擾訊號源週期分析結果--------------------35
3.4 其它各條件之下擺膜激擾訊號週期分析結果圖-------44
3.5 後置翼表面壓力量測結果------------------------46
四、結論-------------------------------------------52
參考文獻-----------------------------------------------54
附錄A 壓力量測結果-------------------------------------55
附錄B 重複性實驗---------------------------------------71
附錄C bimorph激擾控制之量測結果圖----------------------72
附錄D 結論-----------------------------------------------73

【1】Megan,.S.McCluer, Helicopter Blade-Vortex Interaction Noise with Com- parisons to CFD Calculations，NASA Technical Memorandum 110432, 1996.
【2】洪勵吾主持；國立中央大學機械工程研究所，1991翼端渦漩形成與發展之流場觀察，國科會輔助專題研究計劃成果報告，台北。
【3】Horlock,J.H., and Lakshminarayana.,B., 1973 Secondary Flows : Theory , Experim- ent , and Application in Turbomachinery Aerodynamics , Annual Review of Fluid Mechanics ,,pp.247-280.
【4】Fernholz,H.H., External Flow , Topics in Applied Physics : Turbulence , Springer- Verlog Berlin Heidelberg New York, 1978 pp.45-107.。
【5】 Caradonna, F.X.;Strawn , R,; and bridgeman , J.O, An Experimental and Computational Study of Rotor-Vortex Interaction . Vertica , vol.12, no 4, 1988.
【6】Lowson , M.V. ; Progress Towards Quieter Civil Helicopters. Aeronautical Jou- rnal pp.209-223, Jun , 1992
【7】Helicopter Association International (HAI) Fly Neighborly committee. Fly Nei- ghborly Guide HAI ,Feb ,1992
【8】Fredric, H. Schmitz , Reduction of Blade-Vortex Interaction(BVI) Noise through X-Force Control , NASA Technical Memorandum 110371, 1995.
【9】周永根，以壓電薄膜材料控制渦漩－固體表面交互作用之評估研究，碩士論文，2000
【10】方世榮，基礎統計學，華太文化事業股份有限公司，1999台北市