臺灣博碩士論文加值系統

近年來環保意識抬頭，航空噪音問題逐漸受到重視。本文利用數值計算來探討旋翼葉片流場及噪音現象。首先在流場區域建立非結構性四面體網格，然後採用二步及四步Runge-Kutta時間積分法與上風有限體積法求解旋轉座標系統下非穩態三維尤拉方程式。同時，可調網格技巧被用來捕捉渦漩及聲波。為評估本數值求解步驟之準確性，在不同可調網格下探討懸浮狀態時NACA0012翼剖面雙葉片流場且與相關文獻比較葉片表面之壓力係數分佈，此外，由不同切面上之等壓力與等聲值圖可了解噪音現象，最後，在不同時間、不同翼展處及不同線渦漩度下，提出等壓力線圖與等聲壓值圖。這些結果指出，在可調網格上可預測旋翼葉片與指定線渦漩或翼尖渦漩交互作用所產生之噪音。

In the recent year,the sence of environmental protection is on the increase,and the aero-noise problem is gradually emphasized.In this thesis,
the numerical computations are performed to investigate the flowfield and noise behaviors of the rotor blade.First,the unstructured tetrahedral meshes are created on the whole flow domain,then the two-/four-stage Runge-Kutta time integration schemes and a finite volume upwind method are adopted to solve the unsteady three-dimensional Euler equations in a rotating coordinate system.Meanwhile,an adaptive mesh technique is used to capture the vortexed sound wave.To evaluate the present solution procedure,the flowfield for a two-bladed rotor having the NACA0012 airfoil section in hover is studied on the coarse、fine and different adaptive meshes,and the computed surface pressure coefficient distributions on the rotor blade are compared with those in the related literatures.
Besides,the pressure and sound pressure level contours are introduced to understand the noise behaviors.Finally,the contours of pressure and sound pressure level are presented at the different time、span-wise locations and the strengths of line vortex.Those result indicate that the interaction noise between rotor blade and specified line vortex or tip vortex can be predicted on the adaptive meshes.

中文摘要…………………………………Ⅰ
英文摘要…………………………………Ⅱ
誌謝………………………………………Ⅳ
目錄………………………………………Ⅴ
圖目錄……………………………………Ⅶ
符號說明…………………………………Ⅸ
第一章 緒論……………………………1
1.1 簡介…………………………………1
1.2 文獻回顧……………………………1
第二章 研究方法………………………7
2.1 統御方程式…………………………7
2.2 有限體積上風法……………………10
2.3 通量差分分離法……………………11
2.4 重建技巧……………………………14
2.5 時間積分法…………………………15
2.6 邊界條件……………………………18
2.7 噪音分析……………………………19
第三章 網格建立及可調網格技巧……20
3.1 網格建立法…………………………20
3.2 可調網格技巧………………………21
第四章 結果與討論……………………24
4.1 旋翼葉片流之計算…………………24
4.2 旋轉葉片與渦漩之交互作用………26
第五章 結論……………………………30
參考文獻…………………………………77

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