超音速燃燒衝壓引擎由於氣流在進入燃燒室時仍保持高速，讓燃料與空氣保持穩定燃燒成為一個難題。除了加速燃料與空氣混合之外，得知燃料在霧化後於燃燒室內與空氣混合濃度之分布對尋找駐焰位置有很大幫助。本研究欲藉由混合氣體瑞利散射強度與氣體間混合比例有關之特性，進行汽化燃料與空氣混合現象觀測技術的建立。然而航空煤油JP-4為一成分複雜之燃料，故選擇乙烯作為汽化JP-4替代氣體進行研究。
本研究利用校正用觀測艙分別進行氣體混合比例與氣體體積濃度對氣體瑞利散射強度關係觀測，經由實驗結果建立校正用關係曲線。將校正用關係曲線應用於乙烯噴注於超音速流場觀察中，獲得乙烯噴注於超音速流場中與空氣混合之濃度分布。
最後討論此技術應用上如何優化與改進。觀測氣體混合應確定在穩壓狀態下，當氣體壓力變化越大時在氣體混合濃度觀測上的誤差也會越大。觀測儀器收光時間的增加使觀測到的氣體瑞利散射強度增加且可觀測到更多流場細節，代表儀器收光時間能有可調整空間，未來可對此進行改善。

Laser Rayleigh scattering is applied toward measurements of gas visualization, thermometry, and combustion reaction. With the advantages that Rayleigh scattering is elastic and coherent, the signal is easier to detect than Raman scattering and could be enhanced by other factors example: light source. This study discusses the application of laser Rayleigh scattering for measurements in supersonic airflow with hydrocarbon fuel injection. The experimental study is conducted in two different facilities. The correction experiment is conducted in an observation tank and the flow visualization experiment is conducted in in a reflected shock tunnel at National Cheng Kung University. Ethylene become the candidate of the test fuel refer to other studies with similar choice.
The correction of the relationship between gas pressure and signal intensity ensure the signal intensity is proportional to gas pressure. The correction of the relationship between ethylene concentration in air and signal intensity build a correction function for the flow visualization experiment. The measurement about ethylene concentration in mixing gas of ethylene injection in supersonic airflow exist amounts of deviation. Although this method is lack of accuracy about measurement of mixing gas pressure or ethylene concentration, it could measure the structure and forming of ethylene injection in detail. To improve the accuracy of the measurement, block the background noise by moving the pathway of laser light or install more baffle system; Enhance the signal intensity by searching the decent exposure time in ICCD camera.

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