於噴射推進領域中，因液態碳氫燃料具有較佳的熱焓特性，故廣泛地應用於航空器上；但實際應用於超音速燃燒衝壓引擎中，其燃料需在極短時間內與超音速流場進行適當混合燃燒，有其技術上之難度。因此本論文之研究目的即為進一步探討液態燃料之高速液柱在超音速流場中碎裂霧化的變化現象，以提供未來設計超音速燃燒衝壓引擎燃料噴注系統的實際應用參考。本研究設備使用反射式震波風洞，可提供2馬赫(靜溫：1250K、靜壓：1.1 bars)之高焓氣流，可模擬超燃衝壓引擎以馬赫5速度飛行時氣流進入燃燒室的初始條件；實驗選用JP4為主要燃料，噴注流速分別選擇55m/s、69m/s以及85m/s，動量通量比為5.5、7.5以及12.5，研究主要透過視流紋影法(Schlieren photography)與米氏散色光量測方法(Mie scattering)進行實驗觀察。由視流紋影法所拍攝之影像顯示噴流主要可分為前緣穩定區、液氣震盪區以及碎裂消散區；在前緣穩定區觀察到因液柱本身的不穩定性(Nature instability)所產生之表面波動現象；在液氣震盪區內則可觀測到液氣界面之塊狀碎裂現象，以及氣流由迎風處捲入液柱後方所產生尾流(Wake vortices)，使得貼近壁面的噴流分離壁面；而在碎裂消散區內有魚鱗狀結構分布。實驗結果顯示隨著噴流速度增加(即液氣動量通量比愈高)，液柱具有較高的穿透高度、較短之碎裂消散距離與較大之初始震波角度(Shock angle)。此外由雷射散射光量測方法(Mie scattering measurement)進行水平與垂直切面之噴霧結構觀察，實驗結果顯示，垂直切面之影像能進一步觀測到弓形震波前方之迴流區(recirculation zone)，此相對低壓區具有少許的液滴分布。透過不同高度之水平切面之影像拍攝，本研究可進一步建立一三維噴霧影像結構，液柱會隨著切面高度的增加因氣流剪切的作用力使得消散距離快速增加，其液滴分布範圍亦逐漸增大且均勻；若以同一高度之水平切面進行比較，隨著噴注速度增加，噴流會具有較短之消散距離。透過適當的光學觀測技術，本論文已順利完成高速液柱於超音速流場中之碎裂霧化現象觀察，此結果可提供未來超音速燃燒衝壓引擎之設計參考。

關鍵字：超音速燃燒衝壓引擎、反射式震波風洞、視流紋影法、散射光量測方法
 

Liquid fuel injector is an important issue in scramjet combustor design to enhance supersonic flow mixes with fuel. This thesis research utilizes a reflected shock tunnel that provides Mach 2 high enthalpy air flow (static temperature: 1250K, static pressure: 1.1 bar) to simulate scramjet combustor inlet condition. The mixing of fuel(JP-4)/air in a short test time (0.8ms) is experimentally observed. The purpose of this study is to investigate liquid jet breakup process in supersonic flow.
Schlieren photography and Mie scattering are both used to observe the structure of liquid jet spray. The observations indicate that liquid jet breakup is due to the liquid-gas interface fragmentation, shear layer vortices and nature instability of jet. With the increasing momentum flux ratio, the nature instability of liquid jet is enhanced, and, the onset of wake vortices increase the contact area of free stream and fuel that enhances the mixing and shorten the dissipation distance. 2-D Mie scattering shows the liquid jet spray is stretched and starts dissipating from air/spray cone interface. These concluded that the liquid jet breakup mechanism is dominated by shear vortices.

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