請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/47295
標題: | 自動化勢流計算網格應用於船舶之最佳俯仰角分析 An Automatic Grid Generation Program for Potential Flow Code Using in the Optimal Trim Angle Analysis of the Ship |
作者: | Chia-Yen Chiang 江佳燕 |
指導教授: | 郭真祥 |
關鍵字: | 自動網格,勢流,興波阻力,俯仰角, automatic grid,potential flow,wave-making resistance,trim angle, |
出版年 : | 2010 |
學位: | 碩士 |
摘要: | 本研究之目的為建立參數化船形設計軟體程式FRIENDSHIP Framework與 聯合船舶設計發展中心開發之勢流場計算程式USDDCWAVE間所需資料之中介程式,以自動化方式快速產生所需要的船殼網格,並整合於單一平台上,以便最佳俯仰角分析的目標可於短暫工作時程內完成,並建立成資料庫,且能提供實航上即時查詢。
由於勢流場程式對船殼網格的要求,本論文提出曲面網格生成方法:自動找尋多重曲面船殼之邊界,以三次貝茲曲線及曲線弧長進行離散,並於艏部、艉部、及水面處進行局部加密以提升計算精確度。TFI法及投影為形成曲面網格的基礎,同時提供疊代式橢圓方程網格產生法,予以逐次地改善網格變形問題。 本方法首先與聯合船舶設計發展中心提供之CV8250 貨櫃船船型以手動方式產生之網格資料,進行勢流場興波阻力計算結果之比較;並應用於參數化油輪船型43kpc上,以顯示成果應用於不同船型設計的實用性。成果經過網格獨立性測試,可滿足定性上分析的需要。 接著再以同一貨櫃船於靜水中不同航速條件下,於特定俯仰角變化區間內,建構阻力性能圖表。並從圖表中截取出多個船速下之最佳俯仰角,即其最佳的流體動力性能,提供實航上即時查詢,調整壓艙水與貨物至最佳航況之參考。結果顯示俯仰範圍中,每個速度均存在一最佳俯仰角。在滿載狀況下最高可節省12%有效馬力。 Varying trim angle by adjusting the distribution of ballast water to reduce the resistance during real sea operation is considered to be an economic way to save energy. In the thesis CFD approach is chosen to evaluate the resistance of ships running in calm water with different trim angles. The optimal trim angles are recorded as a database for real-time queries. The BEM implementation of CFD approach to solve potential flow problems is faster than FVM. The grids of the hull surfaces and the free surface are required for panel methods. In this report an intermediary program which bridges the gap between the commercial CAD software, “FRIENDSHIP Framework” and the potential flow code from USDDC is built up. The program automatically generates on-surface structural grids as panels’ descriptions, thereby speeding up the process of resistance evaluation. Three key procedures and one refining technique are implemented in the program. The modules are coded in Fscript and C language and they work collaboratively in the FRIENDSHIP Framework. A comprehensive comparison between the automatic grid and the manual grid generated by Gridgen is included. The grid independence of the program has been verified via wave-making resistance coefficients and applied on a containership and a tanker to demonstrate the procedure and algorithm adapted to different hull forms. On the other hand, for each displacement and ship speed there exists an optimal trim angle, which is 11% of total resistance reduction than the even keel condition. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/47295 |
全文授權: | 有償授權 |
顯示於系所單位: | 工程科學及海洋工程學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-99-1.pdf 目前未授權公開取用 | 2.58 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。