Please use this identifier to cite or link to this item: `http://hdl.handle.net/11455/1947`
 標題: 船用管道螺槳之推進效率分析Propulsion Efficiency Analysis of Marine Propeller Ducted Propeller 作者: 許漢宗Hsu, Han-Tsung 關鍵字: Ducted Propeller;管道螺槳;Transport Analysis;Diverged Duct;Propulsive Efficiency;輸送分析;擴管處裡;推進效率 出版社: 機械工程學系 摘要: 欲設計一個具有高推進效率的管道螺槳，須先建立優良的理論基礎， 始克其功。本文乃參照李興軍所提出之拉氏雷諾輸送公式與推進系統動力 功率分析以推導出：通化之管道螺槳的總動力功率、管道螺槳所獲得的動 力功率與推力功率、可用推進功率及推進效率。這些推導出的通化公式中 包含了管道螺槳的加速度、內流場的相對速度與進出口的壓力等效應。值 得注意的是，所推導出的總動力功率中所有的速度項都是相對速度而非絕 對速度。並且，我們定義出「可用推進功率」，以使傳統上誤認的總動力 功率具有確切的物理意義。此外，傳統上利用動量的變化以提昇推力的方 式，易造成相當大的軸流損失，因此本文提出利用擴管升壓的方式來達成 推力的上昇。但實際的三元擴管流非常複雜，並常夾雜管壁附近之回流形 成類似墨西哥帽式之速度分布，並使出口壓力下降及熵值昇高。因此，大 幅擴管並不能確保管道螺槳的推力上昇。未來若能更進一步利用數值模擬 計算擴管後之流場狀態，將更有助於高性能管道螺槳之分析設計。In quest of better propulsive efficiency for ducted propeller, first we must establish genuine theoretical basis. Accordingly, in this paper we refer Lagrangian Reynolds transport equation and propulsion power analysis equationsdeveloped by Hsing-Juin Lee to derive the generalized total kinetic power ofducted propeller, the acquired kinetic power, the thrust power, the availablepropulsion power and associated propulsive efficiency. These generalizedequations involve some physical parameters including acceleration of ductedpropeller, interal flow velocity and inlet/exit pressures. Moreover, it isworthy to note that the total kinetic power is a fuction of relative elocity,not of absolute velocity. Further, we can revive the traditionally mistaken total kinetic power to own true physical meaning by redefining it as availablepropulsion power. Additionally, the traditional scheme of changing flow momentum in order to increase ducted propeller thrust will involve large energyloss in axis flow. In that light, herein we propose to diverge the duct forincreasing the outlet pressure, thus increasing the thrust of ducted propeller. Nevertheless, the genuine 3-D diffuser flow is highly complicated andoftentimes blends with secondary back flows near duct wall to form velocitydistribution as a Mexican chapeau and meanwhile increase entropy. Therefore, overly diverged duct cannot ensure upswing for thrust of ducted propeller.In the future, numerical simulation can give more precise flow status in thediverged region of ducted propeller in order to enhance the relevant propulsion analysis and design. URI: http://hdl.handle.net/11455/1947 Appears in Collections: 機械工程學系所