| 摘要: |
| 为了研究在入口来流马赫数2.52，总温1486K的超声速来流条件下，稳焰凹腔上游不同位置乙烯横向喷注对模型发动机燃烧室内低频燃烧振荡特性的影响，通过1kg/s直连式超燃试验平台，利用高频压力传感器、高速摄影相机等设备，对凹腔上游近距离、远距离喷注等方案的发动机内部压力与火焰动态特性进行了研究。试验结果表明:在当前当量比条件下，当稳焰凹腔上游近距离喷注燃料时，燃烧室存在较大范围亚声速区域，并出现由热声不稳定性激励的低频压力振荡，频率分布范围较宽(50～400Hz)且振幅较弱。对于燃料喷注位置到稳焰凹腔距离较远的情况，燃烧室内出现以火焰逆传和火焰吹脱为特征的周期性火焰振荡现象。分析认为较远喷注距离有利于燃料-空气充分混合并形成预混区，导致火焰快速逆传。火焰逆传与DDT(爆燃转爆震)中的火焰加速传播过程有关。周期性火焰逆传与火焰吹脱过程相耦合形成了具有特定主频(约85Hz)且振幅较大的低频压力振荡。 |
| 关键词: 低频燃烧振荡 喷注位置 稳焰凹腔 热声不稳定性 火焰逆传 火焰加速 爆燃转爆震 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金(11472305；91016028)。 |
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| Effects of Injection Scheme on Low-Frequency Oscillationin a Cavity-Based Scramjet Combustor |
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CUI Xing-da1,SUN Ming-bO2,WANG Hong-bO2,JIANG Xiong1,LI Wei1
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(1. Computational Aerodynamics Institute，China Aerodynamics Research and Development Center，
Mianyang 621000，China;2. Science and Technology on Scramjet Laboratory，National University of Defense Technology，Changsha 410073，China)
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| Abstract: |
| In order to investigate the effects of different ethylene fuel injection location upstream of a cavity flameholder on low-frequency combustion oscillation in a model engine combustor at the inflow conditions of Mach 2.52 with the stagnation temperature of 1486 K， high-frequency pressure sensor and high-speed imaging camera were used to investigate the characteristics of pressure and flame dynamics in an engine under the schemes of fuel injection close or far upstream of a cavity in a direct-connected supersonic combustion test facility with total mass flow rate of 1kg/s. The experimental results suggest that when the fuel is injected closely upstream of the cavity flameholder there exist great range of subsonic flow regions in the condition of present equivalence ratio， and low-frequency pressure oscillation which is driven by thermo-acoustic instability with a broad frequency range of 50～400Hz can occur while the amplitude of oscillation is weak. For the case that distance between the fuel injection and cavity is long， periodic flame oscillation which is charactered by flame flashback and blow-off is observed in combustor. It is suggested that long fuel injection distance is advantageous to sufficient mixing of fuel/air and produces a premixed region from the injection to the cavity， which leads to a rapid flame flashback against the incoming flow. The flame flashback is related to flame acceleration in a deflagration-to-detonation transition procedure. This process couples with the flame blow-off and a low-frequency pressure oscillation can be formed with a specific dominant frequency (about 85Hz) and strong amplitude. |
| Key words: Low-frequency oscillation Injection location Cavity flameholder Thermal-acoustic instability Flame flashback Flame acceleration Deflagration-to-detonation |
