取得制空權為現今各個國家在戰爭狀態下的首要目標，為了達成此
目的擁有性能優越的戰機是缺一不可的條件，而現今對於優越戰機的定
義不外乎為具備隱形功能、能高速飛行，最重要的是還要具備優秀的機
動性，為了提高機動性早期各國無不為自己所研發的戰機加入前置翼
(Canard)，如歐洲各國聯合研發的颱風戰機，法國的飆風戰機，俄羅斯的
SU-33，美國的 HIMAT 計畫皆為前置翼的設計，但當戰鬥機發展到了第
五代戰鬥機後，由於隱形功能這項指標，會增加雷達散射面的前置翼逐
漸被翼前緣延伸(Leading Edge Extension，LEX)所取代，翼前緣延伸的設計本不能像前置翼一樣可以偏轉，但近期俄羅斯所研發的第五代戰鬥機
SU-57 卻出現了第一個全動式翼前緣延伸，為了了解此部件的功能，本研
究將針對SU-57在0.5馬赫下搭配不同攻角與全動式翼前緣延伸向下偏轉
角進行流場現象的探討。
本研究採用三維模型重建目標戰機之三維模型，並運用成本較低的
CFD(Computational Fluid Dynamics)計算流體力學方法來模擬戰機在 0.5III馬赫下搭配不同攻角與全動式翼前緣延伸向下偏轉角的流場現象，其中使用 RANS(Reynolds-averaged Navier-Stokes equation)雷諾平均納維-斯托克斯方程並搭配 Menter SST k-ω 紊流模型來進行模擬，網格部分則是使用六面體網格進行節點劃分。
由於全動式翼前緣延伸在功能與作用方式上與前緣襟翼相同，因此
全動式翼前緣延伸為一種前緣襟翼，且全動式翼前緣延伸主要被設計用
來減少機身阻力與提高機身升阻比，當全動式翼前緣延伸在高攻角時隨
著攻角的增加而更加向下偏轉，進而減少氣流分離的現象並提高高攻角
飛行性能，此外由於全動式翼前緣延伸偏轉後也可提供顯著的低頭力矩，
因此它還可以當作一控制面來控制整機的俯仰動作。

SU-57 is the first aircraft designed with the AML (All Moving Leading Edge Root Extension). It means that it’s LERX (Leading Edge Root Extension) can deflect. Since AML can deflect its relatively large area, some engineers argue that AML is designed to function like a canard that is just blended into the fuselage. Others think that AML is functioning as a leading-edge flap because its deflection angle can be as large as that of a wing leading-edge flap.
To understand the effects iduced by deflecting AML at difference angles of attack, in this study, a SU-57 Like model is designed with different deflection angles in the range from 0 to 15 degree, and angle of attack is set from 0 to 35 degree. A CFD software STARCCM+ is employed to conduct the investigation.
The CFD results show that deflecting AML generally increases lift-to-drag ratio. At higher angle of attack, the flow on the upper surface remains attached with AML deflection. Thus, flow separation is prevented. This is the main reason for the aircraft generating higher lift under conditions of high angle of attack with the deployment of AML deflection.
The results suggest that the AML behaves more like a leading-edge flap. More specifically, it can be regarded as a leading-edge flap for the fuselage because it makes the flow to reattach on the upper surface and significantly improve the lift-to-drag ratio of the V fuselage rather than the wing.

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