隨著航太推進系統對性能要求日益提高，火箭燃燒室內部的熱環境愈趨嚴苛，發展高效能的冷卻技術至關重要。其中，液膜冷卻技術被廣泛應用，作為燃燒室壁面與高溫主氣流間之關鍵熱屏障。然而，針對射流成膜的幾何設計參數與微觀機制，仍缺乏全面性探討。因此，本研究藉由冷流液膜觀測建立後續冷卻設計之物理基礎。
本研究透過改變射流質量流率、孔徑及無因次壁面間距進行單一與雙股射流的冷流實驗，探討上述操作條件對垂直壁面上射流液膜演化及相鄰液膜干涉之影響。同時，導入基於亮度的雷射誘發螢光技術(BBLIF)進行觀測，將液膜螢光影像透過逐像素之線性迴歸模型轉換為厚度分布，以消除Nd:YAG雷射高斯光束空間照度不均所導致的系統誤差，實現定量厚度分析。冷流實驗結果表明，質量流率的提升有助於擴大液膜的橫向與軸向覆蓋範圍；在固定質量流率下，較小孔徑能提高射流的初始速度並增加液膜展開潛力。然而，液膜局部厚度變化並非單調，易受多重參數耦合影響，且在低流率時易產生乾斑。此外，提升無因次壁面間距則會導致射流初始動量散失，可能造成液膜偏轉與液滴飛濺的情況，進而削弱其連續性與覆蓋效能。本研究進一步建立射流雷諾數(Re)、韋伯數(We)與液膜幾何外型之關聯模型，發現韋伯數與無因次最大擴張寬度具備較一致的經驗相關性，可初步預測不同操作條件下的覆蓋極限。雙股射流實驗則證實，相鄰液膜能藉由動量、質量交會有效彌合單一射流易產生之局部乾斑現象。
基於冷流驗證之物理機制，本研究進一步以單孔質量流率2.16 g/s、射流孔徑0.30 mm、無因次壁面間距33.3為參數，完成應用於500磅級液態火箭燃燒室之15孔環形陣列液膜冷卻設計，為液態火箭燃燒室的長效熱防護提供冷流實驗數據與基礎設計。

To advance aerospace propulsion, efficient cooling of rocket chambers is crucial. To establish the foundations of film cooling, single- and dual-jet cold-flow experiments investigated the evolution of the liquid film on a vertical wall. Using Brightness-Based Laser-Induced Fluorescence (BBLIF), a pixel-by-pixel linear regression eliminated errors caused by Nd:YAG laser illumination, yielding quantitative thickness distributions. Results show higher mass flow rates expand coverage, while smaller orifices enhance initial velocity and spreading potential. However, thickness varies non-monotonically, with dry patches forming at low flow rates. Increasing the dimensionless wall distance dissipates momentum, increasing the risk of splashing and reduced coverage. Correlating geometries with Reynolds (Re) and Weber (We) numbers revealed that the We number consistently predicts maximum expansion limits. Furthermore, dual-jet experiments confirmed that merging adjacent films effectively mitigates dry patches by supplementing mass and momentum. Based on these mechanisms, a 15-orifice annular cooling array for a 500-lbf rocket chamber was designed (single-orifice flow: 2.16 g/s, diameter: 0.30 mm, dimensionless distance: 33.3), providing a foundational design for long-term thermal protection.

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