在超音速燃燒衝壓引擎中，進氣流速為超音速，氣流在燃燒室內停留時間極為短暫，因此需再燃燒室內設置駐焰器以提升燃料與氣流之混合效率。在過往支架凹槽駐焰器文獻中藉由數值模擬發現在支架後緣處的流場型態將有利於燃料深入主流場中，然而因燃料注入流場中其分布情況尚未瞭解，本研究利用支架凹槽駐焰器進行噴油實驗，觀察燃料分布現象，並與純凹槽駐焰器進行燃料分布比較。
本研究將利用震波風洞所設置的視流紋影法，並使用研究中定義的分布中心、分布比例及氣流轉折角等參數，觀測燃料的分布情況。實驗模型設計基於先前震波風洞實驗的設計，採用後掠角55°、後緣斜角35°、楔角25°及厚度10mm的支架駐焰器，搭配L/D=3、後壁面角度22.5°的凹槽駐焰器，進行不同槽內前壁面燃料噴注位置及質量流率的噴油實驗。接著，固定支架駐焰器構型，改變長深比為L/D=4、後壁面角度22.5°的凹槽駐焰器，觀察不同長深比對燃料分布的影響。最後，固定L/D=3、後壁面角度22.5°的凹槽駐焰器，比較有無支架駐焰器對於凹槽駐焰器燃料分布的差異。
研究結果得知在L/D=3的支架凹槽駐焰器中，改變燃料噴注位置對燃料分布有顯著影響。噴注孔A因位於支架駐焰器後方，不同燃料質量流率（3、4及5 g/s）下的噴注都能受到支架效應的影響，使燃料分布不僅限於凹槽駐焰器內，更能深入支架駐焰器後緣處的主流場中；而噴注孔B和C僅能使燃料分布於凹槽駐焰器內。當改變長深比由L/D=3至L/D=4並在不同質量流率（3、4及5 g/s）進行比較時，其整體燃料分布效果均不如L/D=3。這是因為氣流轉折角度不同所致，L/D=3支架凹槽駐焰器氣流轉折角較小，剪切層抬升至凹槽駐焰器後斜壁面，使槽內燃料分布較為均勻，並且能使燃料深入支架駐焰器後緣處的主流場中，從而使整體燃料分布範圍更為廣泛。L/D=3支架凹槽駐焰器與L/D=3凹槽駐焰器的氣流轉折角差異，造成燃料分布現象的不同。在L/D=3支架凹槽駐焰器在噴注質量流率3、4及5 g/s時，由於剪切層受支架效應影響抬升，使槽內迴流區擴大，並能夠讓部分燃料深入支架後緣處的主流場中。相較於純凹槽駐焰器，支架凹槽駐焰器能使燃料整體分布更均勻，並深入主流場。

Installing a flame holder in the combustion chamber can enhance the mixing efficiency between the airflow and the fuel. However, both cavity and strut flame holders each face specific challenges when used individually. Previous numerical simulations of strut cavity flame holders have shown that the flow field patterns at the rear edge of the strut are beneficial for fuel penetration into the mainstream flow. Despite this, the distribution of fuel injected into the flow field remains not fully understood. This study uses a strut cavity flame holder for fuel injection experiments to observe fuel distribution phenomena and compares these observations with those from a cavity flame holder.
The experimental model design is based on previous shock tunnel experiments, utilizing a strut flame holder with a swept angle of 55°, a trailing edge angle of 35°, and a wedge angle of 25°, paired with a cavity flame holder with an L/D ratio of 3 and a rear wall angle of 22.5°. The experiments involve varying the fuel injection positions and mass flow rates, as well as changing the length-to-depth ratio. Finally, the differences in fuel distribution between the strut cavity and the cavity flame holder are compared.
The research results indicate that in the L/D=3 strut cavity flame holder, Injector A, located at the rear of the strut flame holder, causes fuel injection at different mass flow rates to be influenced by the strut effect. This results in the fuel distribution extending beyond the cavity flame holder and into the mainstream field at the trailing edge of the strut flameholder. In contrast, Injectors B and C distribute fuel only within the cavity. When the length-to-depth ratio is increased to L/D=4, the overall fuel distribution is less effective than in L/D=3. This discrepancy is attributed to the different airflow deflection angles. Compared to the cavity flame holder, the strut cavity flame holder, due to its smaller airflow deflection angle and the uplift of the shear layer, achieves better penetration into the mainstream field.

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