Fundamental Study of Combustion Oscillations ― ロケット燃焼器を模擬した常圧燃焼器における高周波燃焼振動の Large-Eddy Simulation Large-Eddy Simulation of High-Frequency Combustion Instability in a Laboratory-Scale Rocket Combustor 松山 新吾
Fundamental Study of Combustion Oscillations ― ロケット燃焼器を模擬した常圧燃焼器における高周波燃焼振動の Large-Eddy Simulation Large-Eddy Simulation of High-Frequency Combustion Instability in a Laboratory-Scale Rocket Combustor 松山 新吾
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燃烧振荡的基础研究 - 实验室规模火箭燃烧室高频燃烧不稳定性的大涡模拟 Shingo Matsuyama
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发表时间：
2017
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通讯作者：
R. Frederick
中科院分区：
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作者：
H. Huynh;Brian A. Sweeney;R. Frederick
采用大涡模拟(LES)方法对单组分大气燃烧室的高频燃烧不稳定性进行了模拟。对相应的燃烧实验进行了模拟，并成功地再现了实验中观察到的自激燃烧不稳定性。在大涡模拟中，燃烧室的第一切向(1T)模被激发，压力脉动的幅度和频率与实验观测一致。在LES中观察到1T模的频率为1 kHz，峰-峰幅度约为时均压力的4%。基于大涡模拟结果，探讨了火焰与声速波动之间的耦合机理。未燃烧的H_2/O_2混合气的周期性点火在1T模式频率下产生脉动运动的升压燃烧。这种非定常脉动火焰行为是由燃油喷射和1T型声振荡之间的耦合引起的。瑞利指数表明，不稳定的主要驱动因素是声学耦合的脉动火焰运动。结果表明，大涡模拟能够准确地捕捉到非定常热释放及其与压力振荡的耦合。大涡模拟结果阐明了仅从实验数据不能完全理解的火焰结构的细节，因此对于理解燃烧室中火焰和声学模式的耦合机理是有价值的。
Large-eddy simulation (LES) is performed to simulate high-frequency combustion instability in a singleelement atmospheric combustor. Simulations are conducted for the corresponding combustion experiments, and the selfexcited combustion instability observed in the experiments is successfully reproduced. The first tangential (1T) mode of the combustion chamber is excited in the LES, and the amplitude and frequency of the pressure fluctuations are consistent with the experimental observations. The 1T mode in the LES was observed at 1 kHz and the peak-to-peak amplitude was approximately 4% of time-averaged pressure. The coupling mechanism between the flame and acoustic velocity fluctuations is explored based on the LES results. The periodic ignition of the unburnt H2/O2 mixture produces a lifted combustion in a pulsating motion at the 1T mode frequency. This unsteady pulsating flame behavior is caused by the coupling between the fuel injection and the 1T mode acoustic oscillations. The Rayleigh index indicates that a primary driving factor of the instability is the acoustically coupled pulsating flame motion. The present results demonstrate that the LES can accurately capture the unsteady heat release and its coupling with pressure oscillations. The LES results clarify details of flame structures that are not completely understood solely from the experimental data, and therefore are valuable for understanding the coupling mechanism of the flame and acoustic mode in a combustion chamber.