在超音速燃燒衝壓發動機中，氣流滯留在燃燒室內的時間非常短暫，因此可在燃燒室中裝置支架機構，幫助燃料在短時間內與氣流混合並深入流場分布。本研究利用反射式震波風洞產生 2 馬赫之自由流進行實驗。實驗將改變噴注孔位置與支架的後緣構型，透過視流紋影法分析消散長度，探討楔面渦流以及後緣渦流混合效益的影響。為確保實驗結果不受壁面效應的干擾，本實驗將分為有底座(Base)支架與無底座支架進行。實驗結果顯示，壁面效應會造成流場紊亂，提升混合效益，但會依支架構型與噴注孔距離底座遠近而有不同的影響程度。而楔面渦流與後緣渦流皆能明顯提升燃料與氣流的混合效益，其中後緣渦流影響程度較強；支架會建議採用後緣切斜角支架，並使用靠近支架頂部的噴注孔，以降低壓損，深入流場噴注，並獲取較佳的混合效益。

The velocity of air flowing through the scramjet engine is so high that the residence time of fuel is short, which leads to some critical issues of difficulty in fuel injecting penetration, fuel/air mixing, and flame holding. Strut is a commonly used fuel injection device in scramjet engine to improve fuel penetration and flaming holding. The vortices induced by strut are beneficial for fuel/air mixing. The objective of this thesis research is to observe the mixing behavior of the injected fuel from the strut. This research is conducted in a reflected shock tunnel providing Mach 2 supersonic air flow. The observation of fuel dissipation distance is used to justified the fuel/air mixing effect. The struts used in this experiment are two geometric shapes: Strut with vertical trailing edges and strut with a 35° swept trailing edge are used in the experiment. In order to ensure that the experimental results are not interfered by the wall effect, the experiment is divided into strut with Base and strut without Base for investigation. Concluded from the observations, the Base causes turbulence in the flow field and slightly improve the mixing between fuel and air. Moreover, both the wedge surface vortex and the end vortex significantly improve the mixing, and the effect of the end vortex is stronger. Concluded by using strut with a 35° swept trailing edge with the injection orifice near the top of the strut would have lower pressure loss, better fuel jet penetration, and better fuel/air mixing.

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