潛艦帆罩接面渦漩之數值研究

Numerical Study on the Juncture Vortex Around Submarine Sail-Hull

蔡昇佑(Sheng-Yo Tsai)

指導教授 ： 郭真祥

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.10259

摘要

潛艦在現今海上作戰系統中仍佔有相當的戰略地位。對所有水面艦來說，在海面下活動的潛艦，是個極大的威脅，其威脅性乃來自於潛艦的隱蔽性。由於潛艦所產生的噪音，乃是暴露自己行蹤的隱憂，故各國所發展之潛艦，無不以降低潛艦所產生之噪音為主要考量。而帆罩所產生之接面渦漩，可能流入螺槳作動範圍，使得螺槳入流不均勻。造成螺槳葉片震動，而產生噪音，因此如何降低接面渦漩之影響，亦是達成低噪音螺槳的重要課題。本文先以一利用圓柱來產生接面渦漩之實驗數據，與數值模擬之結果進行比對，初步顯示以數值方法計算接面渦漩之可行性;接著以不同網格點密度，計算由NACA0018翼形斷面建構之柱體與底部平面之接角所產生之接面渦漩，並探討不同網格密度所得之計算結果以及其所造成之差異，用以估計基於時間效益及計算準確度之考量上，於接面渦漩計算所需之較合適之網格點數;接著乃是建立單獨帆罩網格，以CFD方法計算帆罩與船體接面所產生之接面渦漩並加以詳細解析，從而發展一消減接面渦漩產生之方法。其中帆罩外型參考德國209潛艦幾何資料，並以NACA0018翼形斷面為帆罩剖面建構而成。爲考慮接面渦漩與帆罩本身之雷諾數ReL (ReL之範圍=1.07*107~1.17*108之)間之關係，ReL之計算是以帆罩本身長度L=10.4公尺為基礎，經由入流速度之改變確認帆罩接面渦漩位置與雷諾數ReL無明顯關係，再進一步考慮接面渦漩消減機制之建立。此機制乃是於帆罩與船體間另外添加一具有不同坡度之外罩，藉由坡度之調整，觀察不同坡度之消減機制其渦漩之渦漩結構及強度上之改變，嘗試找出有效消減接面渦漩形成之機制，以爲未來帆罩外形設計之參考。

關鍵字

接面渦漩消减機制 ； 接面渦漩 ； 帆罩

並列摘要

Submarine, a type of warship, is designed to operate underwater for a period of time. They are designed to work quietly underwater to avoid detection. For all navy vessels, submarine is a giant threat to its concealment. The noise generated by submarine, is the secret worry of the danger to be detected. So, how to lower the noise generated by submarine is the main consideration .The juncture vortex around the sail-hull, will induce the vibrations of the propeller blades, and then generate noise. In this paper, a circular cylinder, a wing with sections of NACA0018 profile mounted on the plate and a single sail established with the section of NACA0018 which refers to the sail geometry of the German Type 209 diesel-electric submarine, will be used for analyzing the vortex structure by using the CFD method. Then we discuss the vortex phenomenon around sail with Reynolds numbers ranging between 1.07*107 and 1.17*108. Finally, we change the geometry of sail and hope it can be used for reducing the vortex strength.

並列關鍵字

juncture vortex ； sail ； NACA0018

參考文獻

2. 金尚聖、郭真祥、陳彥均、趙修武，“以非穩態CFD方法模擬單獨螺槳實驗之研究”， 第15屆中國造船暨輪機工程研討會，高雄，2003。

3. Baker, C. J., “The Laminar Horseshoe Vortex,” Journal of Fluid Mechanics, Vol. 95, Part 2, 1979,pp.347-367.

4. J.D. Menna, F.J. Pierce , “The Mean Flow Structure Around and Within a Turbulent Junction or Horseshoe Vortex­Part I : The Upstream and Surrounding Three-Dimensional Boundary Layer,” ASME, Vol. 110, DECEMBER 1998.

5. F. J. Pierce , M. D. Harsh, “The Mean Flow Structure Around and Within a Turbulent Junction or Horseshoe Vortex­Part II : The Separated and Junction Vortex Flow,” Journal of Fluids Engineering, Vol. 110, DECEMBER 1998.

6. W. H. Graf , B. Yulistiyanto, “Experiments on Flow Around a Cylinder; the Velocity and Vorticity Fields,” Journal of Hydraulic Research, Vol. 36, 1998.