煤油基燃料W2/過氧化氫(H2O2)作為雙基液態火箭的推進劑具有便宜、低毒性、高熱值及自燃特性，其滴定點火延遲時間約為20ms；而液旋式噴注器機構構造簡單，更能限制氣相反應空間以用來聚集熱能，適合自燃反應速率較緩、滴定點火延遲時間較長的W2/過氧化氫的推進劑組合，但其點火延遲時間及穩定性仍然有待進一步研究。
本研究為了改善液旋式噴注器之點火延遲時間及穩定性，透過針對不同的液旋式噴注器幾何外型設計進行研究，透過改變空腔長度、加入凹槽設計、改變空腔漸縮設計及改變液旋注入角度等，觀察其點火特性與火焰型態，並分析影響其穩定性及點火延遲時間之參數。實驗觀察顯示，在本研究實驗條件下，增加空腔長度可使噴注器擁有足夠的空間聚集熱能到達自燃點火反應，而降低點火延遲時間；透過改變燃料水平注入空腔的角度，使推進劑於空腔內產生噴濺，提升液態推進劑氣化及氣態燃燒反應速率、縮短點火延遲時間；將燃料注入空腔的角度上揚，可促進推進劑的液態之混合效益與觸媒反應速率，可縮短點火延遲時間，並使火焰更加集中。由於液旋式噴注器的火焰會有中空的結構，本研究顯示空腔漸縮的設計能夠集中火焰，有利於縮小未來設計燃燒室的尺寸。
當噴注器多次實驗而不清潔時，空腔內壁會自然被覆黑色錳氧化物；選用噴注器燃料注入角度上揚15度的設計、壁面被覆錳氧化物時實驗，平均點火延遲時間為0.51秒、標準差0.26秒，較無被覆錳氧化物時實驗點火延遲時間縮短約79%、標準差減少約66%，顯示錳氧化物具備有效催化作用，亦顯示內壁錳氧化物鍍膜為未來液旋式噴注器改良之重要研發方向。

The combination of W2(kerosene-base fuel) and hydrogen peroxide is a promising bipropellant system due to its low cost, low toxicity, high propulsive performance, and most importantly hypergolic characteristics. Liquid cyclonic injector is a premixed type bipropellant injector that it is characterized by simple configuration and capability to accrue heat to generate the require auto-ignition in the internal open space. In the injector, liquid fuel and oxidizer are tangentially injected into a small cylindrical chamber to mix. In this research, the relation of injector geometry design and hypergolic phenomena is discussed.
The results show that ignition delay time is reduced either by lengthening the cylindrical chamber or changing the fuel injection angle horizontally and vertically, that enhances the gas phase reaction rate and liquid phase catalytic reaction rate, respectively. Also, using the design of tapering off cylindrical chamber could make plum more concentrated. In each hot-fire experiment, manganese dioxide type of powder-like coverage is found on the inner surface of the cylinder and is removed. Using the design of changing the fuel injector upward by 15 degrees, without removing manganese dioxide coverage shows an averaged ignition delay time of 0.51 seconds and a standard deviation of 0.26 second, which are 79% and 66% shorter and smaller than that of the cleaned ones. This indicates that the manganese dioxide coverage on the wall possesses strong catalytic effect to start the auto-ignition reactions and is an important information for future injector improvement.

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