郭真祥Kouh, Jen-Shiang臺灣大學:工程科學及海洋工程學研究所黃少廷Huang, Sau-TingSau-TingHuang2010-07-142018-06-282010-07-142018-06-282009U0001-1908200914142200http://ntur.lib.ntu.edu.tw//handle/246246/188979本研究主要利用計算流體力學中的二相流方法模擬微泡減阻的現象，其中在貨櫃船船體底部噴入空氣以觀察減阻的效果，將空氣噴口設置於船長方向五個不同位置，再針對各種不同設計方案的計算結果，加以比較分析，以做為微泡噴口位置選用之參考。貨櫃船船型採用台船公司於先前研發計畫中所設計的RD542_2船型，藉助於CFD計算軟體COMET利用在不同含氣率的條件下，計算減阻效果的變化；計算條件採用k-ω紊流模型，在計算時將空氣與水之混合流體以不同含氣率為10%到90%之間在球形艏後緣噴出，以探討含氣率對於減阻效果所產生的影響，其中發現含氣率為10%~20%時，有較佳的減阻效果。接著設計其他四種不同位置之開口，初步觀察在不同開口使用相同含氣流體時，含氣流體之流動軌跡與產生之減阻效果。最後綜合比較三種不同船速、三種不同噴氣速率、三種不同含氣率與四個不同開口彼此之間減阻效果與噴氣量的關係，其中發現開口之噴氣方向垂直向下所產生的減阻效果較開口之噴氣方向偏向船側為佳，且船速較高時可以容許較高含氣流體注入流場並產生較佳的減阻效果。This study conducted simulations of injecting air and water into the flow field around a container ship by two-phase flow method of computational fluid dynamics (CFD). In order to understand behavior of air-water mixed fluid in different flow conditions, many conditions were investigated and analyzed. The influence parameters were taken into account , including injection velocities, void fractions of air , ship speed and injection positions . These results were helpful to determine which position and condition is better for drag reduction. BSL k- turbulence model and CSBC RD542_2 model were used to proceed numerical computing . At first , the design condition of void fraction of air were set between 10% to 90% , and inject position were at the end of bulbous bow. It has been shown that the drag reduction rate will decrease when void fraction of air increase and void fraction between 10% to 20% has better reduction rate. Then we used constant air-water ratio fluid (10%) to inject into four other different positions and compared the track of bubble flow with friction reduction rate . t last , we want to observe how the other influence factors can effect friction reduction rate . So the conditions of three different Froude number , three different jetting velocities , three different void fractions of air and four different positions were desighed to compute and compare the results with friction reduction rate. Among these results , we found that the reduction capability was better when the jet direction faced downward ship hull rather then toward hull side. And when ship speed increase , the flow field can allow injecting more air quantity as well as producing higher friction reduction rate.摘 要 IIIBSTRACT IV 錄 V目錄 VIII目錄 XIII一章 緒論 1.1前言 1.2文獻探討 5.3動機與目的 11.4論文架構 12二章 理論基礎 13.1統御方程式 13.2紊流模型 14.3壁函數 16.4數值離散方法 18.5自由液面計算 20.6船殼受力計算 20.7平行計算 21三章 計算方法與驗證 22.1船型尺寸介紹 22.2計算網格之建構 23.3邊界條件設定 24.4網格分布策略 26.5計算條件 28.6摩擦力驗證 28四章 計算結果與分析 32.1微泡減阻技術應用於貨櫃船之計算(不考慮浮力) 32.1.1計算條件與設定 32.1.2計算結果 33.2微泡減阻技術應用於貨櫃船之計算(有考慮浮力) 38.2.1計算條件 38.2.2計算結果 38.2.3結果探討 41.3不同開口位置之減阻效果計算 42.3.1一號開口之結果 43.3.2二號開口之結果 44.3.3三號開口之計算結果 45.3.4四號開口之計算結果 46.3.5五號開口之計算結果 48.4不同航行速度對微泡減阻之影響 50.4.1航速10節( Fn = 0.13 ) 50.4.2航速20節( Fn = 0.26 ) 62.4.3航速30節( Fn = 0.39 ) 72.4.4空氣覆蓋狀況總比較 79.5噴氣量與減阻效果之關係 80.5.1 Fn = 0.13 之比較結果 80.5.2 Fn = 0.26 之比較結果 82.5.3 Fn = 0.39 之比較結果 84五章 結論 87考文獻 895601447 bytesapplication/pdfen-US微泡減阻貨櫃船數值模擬二相流micro-bubbledrag reductionnumerical simulationCFDthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188979/1/ntu-98-R96525043-1.pdf