邱逢琛臺灣大學：工程科學及海洋工程學研究所吳昌政Wu, Chang-ChengChang-ChengWu2007-11-262018-06-282007-11-262018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/51143本研究著眼於魚類尾鰭推進的力學機制，以穩態小板法為基礎，擴充至二維振動翼非穩態流場計算，建構尾緣渦流模式及數值計算程式，先與Theodorson的二維薄翼振動解析解進行比較，以驗證本方法的正確性。其次，再引用Triantafyllou所進行的二維翼起伏與縱搖耦合運動下的推力係數、功率係數及推進效率之系列實驗分析結果作為比較驗證的依據。各種起伏振幅、名目攻角及史徹赫數的系列計算結果顯示名目攻角越小其效率越高之趨勢。而在名目攻角固定下，起伏振幅越大則推進效率越佳。此外，產生最佳效率的史徹赫數約在0.15附近，此計算結果與Triantafyllou的實驗所顯示，在小攻角狀態不發生前緣剝離渦流的條件下所得到的結果是一致的。但是在大振幅與大攻角的運動狀態下，其推進效率的理論計算值與Triantafyllou的實驗值則有較顯著的差異，其原因在於前緣剝離渦流發生的效應尚未納入本研究的渦流模式中予以適當模擬所致。Based on the steady panel method, this study explores the mechanism of caudal fin and further explains oscillation foils under two dimensional unsteady flow field. The validity of the presented study method is compared with the theoretical analysis of the two-dimensional flat plate foil from Theodorson, and with the experimental results from Triantafyllou by examining the thrust coefficient, power coefficient, and propulsive efficiency of a two-dimensional foil under heaving and pitching motion. A series of calculation suggests that the smaller the nominal attack angle, the greater the propulsive efficiency. In addition, the results indicate that the best efficiency is yielded when Strouhal number equals approximately 0.15, which agrees to the results from Triantagyllou’s experiment where no leading edge vortex was assumed. Nevertheless, under large heave amplitude and large attack angle, the propulsive efficiency from the presented study method differs significantly from that of Triantafyllou’s experiment. This is due to the lack of consideration of the leading edge vortex in the wake model presented.中文摘要-------------------------------------------------一 英文摘要-------------------------------------------------二 目錄-----------------------------------------------------三 表目錄---------------------------------------------------六 圖目錄---------------------------------------------------七 符號說明-------------------------------------------------九 第一章 緒論---------------------------------------------1 1.1 研究背景--------------------------------------------1 1.2 文獻回顧--------------------------------------------2 1.3 本文架構--------------------------------------------3 第二章 理論基礎-----------------------------------------4 2.1 座標系----------------------------------------------4 2.2 振動翼的主要運動參數--------------------------------4 2.3 統御方程式及邊界條件--------------------------------6 2.4 流體動力係數及性能係數------------------------------8 第三章 數值計算方法------------------------------------11 3.1 翼形的位置與姿態-----------------------------------11 3.2 離散化---------------------------------------------12 3.3 跡流模式-------------------------------------------13 3.3-1 跡流的位置-------------------------------------13 3.3-2 跡流的強度-------------------------------------14 3.3-3 跡流項的速度勢---------------------------------14 3.3-4 跡流項的離散化---------------------------------15 3.4 翼形表面切線速度-----------------------------------15 3.5 流程圖---------------------------------------------17 第四章 計算結果與討論----------------------------------18 4.1 供試翼形-------------------------------------------18 4.2 計算條件-------------------------------------------18 4.3 數值計算-------------------------------------------19 4.3-1 小振幅簡諧起伏運動-----------------------------19 4.3-2 起伏振幅 =0.25與縱搖耦合之運------------------20 4.3-3 起伏振幅 =0.5與縱搖耦合之運動-----------------20 4.3-4 起伏振幅 =0.75與縱搖耦合之運動----------------20 4.3-5 相同攻角、不同起伏振幅之間的比較---------------- 21 4.4 數值計算與實驗數據之比較--------------------------- 21 4.4-1 推進係數與推進效能之比較----------------------- 21 4.4-2 實驗數值與非黏性流之比較-----------------------22 第五章 結論與展望--------------------------------------24 參考文獻-------------------------------------------------26 附錄A----------------------------------------------------53 附錄B----------------------------------------------------57 附錄C----------------------------------------------------58981009 bytesapplication/pdfen-US史徹赫數推進效率尾鰭振動翼小板法panel methodoscillation foilscaudal finStrouhal numberpropulsive efficiencythesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/51143/1/ntu-93-R90525009-1.pdf