Dynamic mode decomposition analysis of detonation waves

Dynamic mode decomposition analysis of detonation waves
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爆轰波动力模态分解分析

DOI:
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发表时间:
2012
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通讯作者:
P. Ravindran
P. Ravindran
中科院分区:
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文献类型:
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作者:
L. Massa;R. Kumar;P. Ravindran

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动态模式分解用于研究横向不稳定爆炸支持的自激波动。本研究的重点是极限环解的稳定性及其对强迫的响应。非受迫条件的 Floquet 分析表明,最不稳定的扰动几乎是次谐波,全局模式与基频之间的比率 λi/ωf = 0.47。这表明周期倍增模式的出现是在较大系统中观察到的混沌途径。根据四种基本能量模式的一致性来分析对强迫的响应:声学、熵、动能和化学。模态分解的结果表明,自激振荡对涡旋强迫相当不敏感,并且在强迫湍流马赫数达到 0.3 时仍能保持其相干性。
Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the stability of the limit cycle solutions and their response to forcing. Floquet analysis of the unforced conditions reveals that the least stable perturbations are almost subharmonic with ratio between global mode and fundamental frequency λi/ωf = 0.47. This suggests the emergence of period doubling modes as the route to chaos observed in larger systems. The response to forcing is analyzed in terms of the coherency of the four fundamental energy modes: acoustic, entropic, kinetic, and chemical. Results of the modal decomposition suggest that the self-excited oscillations are quite insensitive to vortical forcing, and maintain their coherency up to a forcing turbulent Mach number of 0.3.