液態雙基推進火箭具有高燃燒效率、高比衝值、可重複點火與推力可控的特性，在國外已經發展許久，並且都有豐富的研究成果，因此發展液態雙推進火箭勢在必行也是目前相當重要的課題。國內目前對於液態雙推火箭的研究不多，由於液態氧需要克服低溫儲存的問題，還無法直接使用，因此想藉由先操作氧化亞氮來當作過渡的氧化劑，以提升對液態火箭的掌握度。氧化亞氮為高蒸氣壓的氧化劑，具有獨特的熱物理特性造成的閃蒸霧化，雖然與液態氧的熱力性質還是稍有差異，但優點是在常溫下就可以操作，大幅減少研究的門檻。而同軸式噴注器的特點為用在異相推進劑(液氣相)，因此想藉由氧化亞氮本身的熱物理特性搭配同軸式噴注器將煤油霧化。本研究目的在於探討以液態氧化亞氮/煤油作為雙推進劑，利用液態氧化亞氮本身的熱物理性質搭配同軸噴注器促使煤油破碎並混合，藉由冷流實驗觀察，整理及比較氧化亞氮噴注與混合噴注行為，以及孔數與孔距對於噴霧的影響來作為後續熱流實驗的基礎。
而從單一氧化亞氮的實驗噴霧都比經驗公式預估的略小，但噴霧寬度的趨勢接近，而由質量守恆定律計算的不同橫截面面積下的空間密度證明氧化亞氮在噴注不到1mm的位置就大部分已經汽化成氧化亞氮氣體，有助於與中心燃料的混合。無論4孔或6孔隨著孔距的增加，混合後的液體核心長度會越來越長，而混合的中心燃料擴散角度會越來越小；在相同孔距下，6孔的核心長度都比4孔的來的短，而噴霧角度6孔的都比4孔的來的大。綜合陰影法與PLIF的混合噴霧並計算O/F ratio的範圍得知，孔距與孔數都會影響O/F ratio的範圍。在無論4孔或6孔在相同與噴注器的距離中，隨著孔距的增加O/F ratio所包含的範圍越小；在相同孔距的情況下，6孔的實驗結果都比4孔所包含的O/F ratio範圍來的大。混合噴霧在4_4、4_5與6_5實驗中的O/F ratio範圍差異不大，推測氧化亞氮影響中心燃料噴霧如果脫離氧化亞氮的膨脹區，那麼混合效果有限。

Liquid bipropellant rockets have high combustion efficiency, high specific impulse, re-ignition capability, and controllable thrust. While these technologies are well-developed internationally, there is limited domestic research due to the challenges of cryogenic storage of liquid oxygen. On the other hand, nitrous oxide has similar thermodynamic characteristics with somewhat mild oxidation performance and can be operated in room temperature without cryogenic cooling. Therefore, nitrous oxide is considered as a suitable oxidizer candidate prior to transition to liquid oxygen to improve understanding of liquid rockets. Nitrous oxide, a high vapor pressure oxidizer, offers the advantage of operating at room temperature, reducing research barriers. The study aims to use nitrous oxide’s thermal properties with a coaxial injector to atomize kerosene. Cold flow experiments observe the effects of injector hole number and spacing on spray, forming a basis for future hot flow experiments. Experiments with nitrous oxide show spray widths slightly smaller than empirical predictions but with similar trends. Mass conservation calculations reveal that nitrous oxide vaporizes mostly within 1mm of injection, aiding central fuel mixing. Both 4-hole and 6-hole configurations show that increased hole spacing lengthens the mixed liquid core and narrows the central fuel diffusion angle. At the same hole spacing, the 6-hole configuration produces a shorter core length and larger spray angle than the 4-hole configuration. Shadowgraph and PLIF mixing sprays, along with O/F ratio calculations, indicate that hole spacing, and number affect the O/F ratio range. Increased hole spacing narrows the O/F ratio range, while the 6-hole configuration covers a broader range than the 4-hole configuration. The O/F ratio range in the 4_4, 4_5, and 6_5 experiments show minor differences, suggesting that nitrous oxide's influence on the central fuel spray is limited if it extends beyond the nitrous oxide expansion region.

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