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    Title: Numerical investigation of aerodynamic efficiency for spiroid winglet with blowing
    Other Titles: 螺旋狀翼尖小翼之空氣動力數值模擬
    Authors: 連魁文;Lien, Kuei-wen
    Contributors: 淡江大學航空太空工程學系碩士班
    宛同;Wan, Tung
    Keywords: 翼尖渦流;誘導阻力;螺旋狀翼尖小翼;噴流;Trailing vortex;Induced drag;Spiroid winglet;Blowing
    Date: 2006
    Issue Date: 2010-01-11 06:53:13 (UTC+8)
    Abstract:   自從1976年Richard T. Whitcomb的研究報告指出加裝了翼尖小翼(Winglet)的飛機,其空氣動力性能較加裝一般翼尖裝置更能明顯提高後,翼尖小翼便成為改善飛機空氣動力性能的主要方法;因為,購買一架飛機的成本之高而令飛機的服役年數必須長達一、二十年以上,方符合經濟利益,所以不大改變機體結構,而又能顯著提升飛機性能,便成為翼尖小翼的最大優勢。翼尖小翼的概念相當簡單─阻擋下翼面上翻的翼尖渦流,減低下洗流效應的影響,故能減低誘導阻力;一般長程客機巡航時,誘導阻力佔總阻力的百分比可高達35%左右,如能有效降低誘導阻力,對總體性能的提高來說是相當可觀的。
      本論文以計算流體力學的方式,利用現有的、強大的計算流體力學商業軟體FLUENT進行對加裝了最新翼尖小翼概念─螺旋狀翼尖小翼的機翼之模擬,探討其應用於一般商務客機於次音速馬赫下、不同攻角時,其空氣動力性能之變化;同時亦嘗試施加噴流在翼尖附近,以期進一步提升飛機之總體性能。吾人採用之機翼乃Gulfstream Ⅳ此一小型長程客機的主翼參數,而其翼剖面則是採用Whitcomb所設計的超臨界翼剖面(Supercritical Airfoil),以此做為基準,比較未安裝、安裝螺旋狀翼尖小翼和安裝且施加噴流三種情況在巡航馬赫數0.8時,攻角0度到13度之間的升力係數、阻力係數和升阻比;其中螺旋狀翼尖小翼又依其環狀小翼的位置分為前旋與後旋兩種情況。
      翼尖渦流對飛安的影響眾所周知,施加次音速流速的噴流於翼尖部分則是希望加速潰散翼尖渦流,並研究其對空氣動力性能的影響,而最終的目的是要找出減阻最多並且有效潰散渦流強度的最佳化結果,不僅提升飛行效率,也能改善飛行安全,甚而提高機場的使用效率。
    Since 1976 Richard T. Whitcomb has shown that the efficiency of the aircraft equipped with winglet is better than other devices set at the wingtip, winglets are now incorporated into most new commercial and military transport jets. The concept of the winglet is very simple, disconnecting the roll-up vortices from the lower wing surface. A typical civil transport aircraft reveals that the skin friction and lift induced drag together represent more than 80% of the total drag, they constitute of two main sources of drag, approximately one half and one third of the total drag for a typical long range aircraft at cruise conditions.
    In this thesis, use computational method, and employ FLUENT software as flow solver. Using in computation the geometry of the wing is of Gulfstream IV, and its airfoil is chosen of Whitcomb’s supercritical airfoil. And the scale of spiroid winglet is described by using the height of wing span. In our case the height of spiroid winglet is about 4% of wing span. The cases we calculated including eight angles of attack, 0, 2, 4, 7, 9, 11, and 13 degrees. The three different configurations are the bare wing of no wing tip device, the wingtip equipped with spiroid winglet, and blowing on the spiroid winglet. From literature the maximum cruising speed of Gulfstream IV is of Mach number 0.85 and the economic cruising speed is of Mach number 0.8. So the speed in this computation is set at 0.8 of Mach number.
    The goal of blowing at the wingtip is to advance the customary time of decaying trailing vortices and reduce the strength of trailing vortices. We wonder what happened as the spiroid winglet and blowing at wingtip coupled together, and finally find a optimal result that reduced the total drag as well as the strength of the trailing vortex, thus the flight become safer, the fuel consumption become more efficiency, and the capacity of the airport could be bigger.
    Appears in Collections:[Graduate Institute & Department of Aerospace Engineering] Thesis

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