氧化亞氮沒有毒性，並且具有自加壓的特性，能夠簡化系統、降低操作成本，是常見的推進劑選擇。然而氧化亞氮因為容易汽化使流體具有氣體的可壓縮性，當下上游壓力比值達到臨界值時導致密度變化形成阻流(choked flow)而降低流量。此外，噴霧也呈閃蒸噴霧(flashing spray)狀態，液體自噴注器噴出噴霧張角容易迅速大幅擴張，且液滴的顆粒比較小。本研究的目的為藉由冷流實驗探討氧化亞氮熱力性質對其噴霧和流量的影響。分別以過熱程度(Rp)（用來描述描述流體具備從液相到氣相的熱力性質變化之能量高低的參數，以流體溫度對應的飽和壓力跟外界壓力的比值表示）為 30、40、50和60的氧化亞氮進行上游壓力最大到65 bar的噴霧實驗。
從實驗結果發現，氧化亞氮大致可以飽和壓力跟下游壓力的關係作為區別在不論是噴霧還是流量方面都呈現兩種趨勢。Rp=30和40的氧化亞氮閃蒸型態落在外部閃蒸噴流(external flashing jet)和完全閃蒸噴流(fully flashing jet)的過渡區間，導致其噴霧形態不穩定在兩種噴霧之間變化，而Rp=50和60時已達到完全閃蒸噴流。氧化亞氮流量隨上游壓力增加越傾向於不可壓縮流液體，飽和壓力為30和40 bar的氧化亞氮因為不易汽化，上游壓力越大汽化程度越低，然而飽和壓力為50和60 bar時則是因為上游壓力增加形成類似液體擾動翻轉(hydraulic flip)的現象，噴注器內氣腔和中心液體之間有較明顯的邊界。噴注器內的空蝕(cavitation)現象不只影響流量，對噴霧的穩定性也有影響，空蝕現象越劇烈對噴霧的擾動越大導致噴霧張角忽大忽小，然而達到液體擾動翻轉時，擾動減緩使得噴霧張角維持不變。
此外，噴注器噴注管長度(l)對流量和噴霧型態的穩定性也有影響，當長度越短流量越大，但此效應隨上游壓增加而減緩，此外Rp=40的氧化亞氮噴霧型態在l/d=0.5噴注器最不穩定。
從實驗結果可知上游壓力和噴注器設計都會影響氧化亞氮噴霧，然而飽和壓力跟下游壓力的關係是影響流量變化跟噴霧最關鍵的因素。

Nitrous oxide is a highly anticipated green propellant due to its non-toxicity and self-pressurizing characteristics. The purpose of this study is to investigate the influence of thermodynamic properties of nitrous oxide on its spray and flow rate.
From the experimental results, it is found that nitrous oxide shows two distinct trends in both spray characteristics and flow rate by the relation between saturation pressure and downstream pressure. Nitrous oxide with Rp = 30 and 40 falls within the transitional region between external flashing jet and fully flashing spray jet. Also, at Rp = 50 and 60 nitrous oxide exhibits fully flashing jet. The flow rate tends to behave like incompressible liquid flow as the upstream pressure increases. For nitrous oxide with saturation pressure = 30 and 40 bar, the cavitation decreases with increasing upstream pressure. On the other hand, for nitrous oxide with saturation pressure = 50 and 60 bar, the cavitation is intensive enough to form hydraulic flip as the upstream pressure increases. The cavitation within the injector not only affects the flow rate but also the stability of the spray’s size. More intensive cavitation results in greater disturbance to the spray, causing fluctuations in the spray cone angle. However, when the hydraulic flip is achieved, the disturbance is constrained, and the spray cone angle remains constant.

郭鎧嫻, 20牛頓級氧化亞氮/甲烷雙基氣體推進系統設計 = Development of a 20 Newton N2O/CH4 Gaseous Bipropellant Thruster. 國立成功大學航空太空工程學系, 2020.
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