Oscillatory combustion representative of thermo-acoustic instability in liquid rockets is simulated by experiment and LES calculation to investigate the flame behavior in detail. In particular, we focus on how the velocity and pressure fluctuations affect the behavior of the dense oxygen jet, or ‘LOx core’. The test case investigated is a high pressure, multi-injector, oxygen-hydrogen combustor with a siren for acoustic excitation. First, the LES calculation is validated by the resonant frequencies and average flame topology. A precise frequency correction is conducted to compare experiment with LES. Then an unforced case, a pressure fluctuation case, and a velocity fluctuation case are investigated. LES can quantitatively reproduce the LOx core shortening and flattening that occurs under transverse velocity excitation as it is observed in the experiments. On the other hand, the core behavior under pressure excitation is almost equal to the unforced case, and little shortening of the core occurs. The LOx core flattening is explained by the pressure drop around an elliptical cylinder using the unsteady Bernoulli equation. Finally, it is shown that the shortening of the LOx core occurs because the flattening enhances combustion by mixing and increase of the flame surface area.

通过实验和LES计算模拟了代表液体火箭中热声不稳定性的振荡燃烧，以详细研究火焰行为。特别是，我们专注于速度和压力波动如何影响致密的氧气射流或“ LOx芯”的行为。研究的测试用例是带有警报声的高压，多喷射器，氧气-氢气燃烧器。首先，通过共振频率和平均火焰拓扑来验证LES计算。进行精确的频率校正以与LES进行实验比较。然后研究非受力情况，压力波动情况和速度波动情况。LES可以定量地再现在横向速度激励下发生的LOx芯的缩短和变平，正如在实验中观察到的那样。另一方面，在压力激励下的芯行为几乎等于未受力的情况，并且几乎没有发生芯的缩短。LOx核心扁平化是通过使用不稳定Bernoulli方程的椭圆圆柱周围的压降来解释的。最后，显示出LOx芯的缩短是因为扁平化通过混合和增加火焰表面积而增强了燃烧。LOx核心扁平化是通过使用不稳定Bernoulli方程的椭圆圆柱周围的压降来解释的。最后，显示出LOx芯的缩短是因为扁平化通过混合和增加火焰表面积而增强了燃烧。LOx核心扁平化是通过使用不稳定Bernoulli方程的椭圆圆柱周围的压降来解释的。最后，显示出LOx芯的缩短是因为扁平化通过混合和增加火焰表面积而增强了燃烧。