本研究以煤油(kerosene)/過氧化氫(H2O2)之組合做為雙基火箭推進劑，其具備高推進性能(C*>1400m/sec；Isp>280sec)與儲存性。相較於MMH/ NTO 推進劑組合，煤油/過氧化氫系統具無毒、低腐蝕性且便宜等優點，為具競爭力、低污染之綠色推進劑組合。煤油/過氧化氫為高O/F ratio(3~5)之火箭推進劑組合，因兩噴流動量差異過大，以雙衝擊式霧化機構無法獲得適當的霧化效果，產生較高的混合效率(Em)及推進性能(特徵速度C*)。本研究針對高O/F ratio之推進劑組合，以四噴流二階段式衝擊(同質雙衝擊)作為噴注機構之基本設計概念，以改善混合效率，探討各設計參數對混合效率的影響。
本研究以純水作為過氧化氫之模擬液，改變衝擊角(θ=30˚,45˚)、孔口直徑(d=0.52mm,0.55mm,0.6mm)、衝擊距離(l=10mm,15mm,20mm)；煤油固定衝擊角θ=30˚、孔口直徑d=0.3mm，改變衝擊距離(l=3mm,5mm)，於O/F ratio=3~5分別進行同質雙衝擊實驗。在不同設計參數下，假設兩同質雙衝擊之液滴不互相干擾，利用疊合的方式預測真實四噴流衝擊的混合效率及平均特徵速度。選出最佳平均特徵速度做四噴流衝擊的參數組合，探討實際四噴流衝擊與預測值的差異，並驗證疊合預測方式的可靠性。
實驗觀察顯示，煤油表面張力較小，較易因空氣與流體動力不穩定性而碎裂，產生較小的液滴且均勻分布於霧化範圍內；純水(過氧化氫模擬液)表面張力較大，未霧化的液體互相擠壓延伸，導致霧化質量分布較狹長且集中。就設計目的而言，O/F ratio=4，純水在衝擊角θ=45˚、衝擊距離l=20mm、孔徑d=0.55mm、衝擊點下游距離zo=10mm之霧化截面，與煤油衝擊角θ=30˚、衝擊距離l=5mm、孔徑d=0.3mm、衝擊點下游距離zf=20mm之霧化截面疊合為產生較佳特徵速度(1565.8m/s)之組合。將此設計組合以實際四噴流衝擊量測顯示：煤油霧化後之液滴於第二衝擊點時被質量集中的純水推開，導致霧化截面中心區域O/F ratio偏高，但因高O/F ratio值對平均特徵速度影響較小，故實際平均特徵速度(1584m/s)大於預測平均特徵速度。即使噴霧軸上煤油發生被推開的現象，此參數組合仍為本實驗參數範圍內產生較佳特徵速度之設計。

Compare to the MMH/NTO rocket propulsion systems, kerosene/ H2O2 propellants have the advantages of non-toxicity, lower cost and corrosion, yet still possess adequate propulsive performance¬. In the design of the injector for kerosene/ H2O2 rocket engines, the high mass flow ratio between H2O2 and kerosene (ratio=3~5) makes the conventional unlike-doublet impinging design impropriate to atomize and mix of the pro-pellants. In this study, for high O/F ratio liquid rocket propulsion systems, a two-stage like-doublet imping¬ing technique has been researched, and discussions of some design parameters to the mixing of the propellants has been included.
In the study, water is used as the stimulant of H2O2. The orifice for kerosene injection is fixed to 0.3mm, while water injection orifices are varied (0.52, 0.55 and 0.6mm). The impinging angle (30 and 45 for water impingement, and 30 for kerosene impingement), and distance between orifices (10mm, 15mm and 20mm for water impingement, and 3mm and 5mm for kerosene impingement) are also varied to investigate their effects on the mass probability distribution and uniformity of the impinging spray. By assuming the droplets of the sprays from two individual like-doublet impingements are without interactions, predictions of the local mixture ratio distribution, mixing efficiency, and characteristic velocity of each two-stage injector configuration is made by simply overlap the mass distributions of the two like-doublet sprays, where planner laser induced florescence (PLIF) technique is incorporated to determine the mass distribution of the droplets in the sprays.
The results show that the droplets of kerosene sprays are smaller and denser than that of water sprays due to its low surface tension. The best characteristic velocity (1584m/s) appears at O/F ratio of 4, where the two-stage injector design configuration is set at water (0.55mm orifice) impinging angle of 45˚ and 30˚ for that of kerosene (0.3mm orifice). In the configuration, the distance between two orifices of water and kerosene injections are 20mm and 5mm, respectively, and the distance of the impinging points of water and kerosene was 20mm and 10mm. The observation shows the droplets of first-stage (kerosene) impinging sprays are always pushed toward the rim by the droplets of the second-stage impinging sprays, results in higher local O/F ratios near the center of the sprays, however, has little effect on the characteristic velocity of the kerosene/ H2O2 propellant system. Although the phenomena of droplet interactions in this two-stage impinging design are unavoidable, overlapping the mass distributions of the two like-doublet sprays to achieve the injector configuration is still adequate.

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