在超音速燃燒衝壓引擎中，由於燃料於燃燒室停留時間極為短暫，因此需在流場中設置一駐焰機構。為了減少全壓的損失，選擇以凹槽駐焰器產生低速迴流區，供燃料於此進行燃燒。本研究首先觀察冷流場中液態燃料於凹槽內外之噴注情形及分布狀況。再進行槽內不同位置點火器放置之燃燒實驗，找出槽內駐焰之最佳位置及噴注條件，使槽內流場受點火器氣流影響最小且穩定駐焰。有了槽內駐焰之成功條件，再加入上游主噴注進行燃燒駐焰實驗，並對主噴注成功駐焰之結果加以分析。冷流實驗結果顯示槽內斜向45度角噴注能使燃料噴注於剪切層之高速環境而具有較佳的碎裂霧化效果及更多的空氣接觸機會，有別於水平噴注之槽內低速環境缺乏氣流交換，因此以槽內45度角斜向噴注進行燃燒實驗。熱燃實驗中，槽底距前壁面15 mm處點火具有較佳的槽內加熱效果及迴流環境，流場較不受點火器之氣流影響；而斜壁面點火之火焰易受剪切層進入之高速氣流影響，於斜壁面甩盪使流場混亂，不利於駐焰的進行。由實驗結果推論槽內JP4噴注質量流率4 g/s連續駐焰條件為槽底溫度需達1111 K，槽底壓力標準差0.1883以下，以及無一特定頻率強度之壓力震盪擾亂流場，則可駐焰至供油結束。在槽內JP4質量流率4.5 g/s斜向噴注，再加入上游主噴注質量流率8 g/s，可獲得最高之駐焰溫度1222 K，並且成功穩定駐焰長達15秒。因此以此配置作為本研究最佳駐焰參數選擇，達成以點火器點燃槽內燃料噴注作為母火，引燃上游主噴注之超音速燃燒目標。

In a supersonic combustion ramjet, since the fuel stays in the combustion chamber for a very short time, it is necessary to set a cavity flame holding mechanism in the flow field for the liquid fuel to be fragmented, atomized and burned. In this study, the direct wind tunnel of National Cheng Kung University's Guiren campus was used to generate a supersonic flow of Mach 2, total temperature 780 K, and total pressure 122 psi, observing JP4 fuel injection and flame holding. First, observing the fuel distribution situation and the reaction of fuel between inside and outside cavity in the cold flow. Then the flame-holding experiment of combustion with liquid cyclonic igniter was carried out. The experimental results show that the igniter at the bottom and 15mm from the front cavity wall has better heating effect and recirculation environment. By injecting 4.5 g/s of JP4 obliquely in the cavity, and adding 8 g/s of the upstream main injection, the highest flame holding temperature of 1222 K was obtained, and the flame holding was successfully stabilized for 15 seconds. Therefore, this configuration was selected as the optimal flame holding parameter in this study, and the supersonic combustion goal of igniting the upstream main fuel injection was achieved by using the fuel injection ignited by the igniter in cavity as the mother fire.

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