Abstract

The results of numerical study of supersonic flow in a channel with cavity are given. The calculated oscillation spectra are analyzed using the fast Fourier transform. Two types of oscillatory modes can be distinguished in the resulting periodic self-oscillatory regime. The first type of the modes corresponds to acoustic vibrations caused by the passage of sound waves along the cavity and calculated using the modified Rossiter formula. The second type of the modes corresponds to the frequencies of flow-rate oscillations caused by mass transfer between the cavity and the external flow. It is shown that the flow structure is modified when fuel is supplied in front of the cavity. Active combustion occurs in the layer of mixing fuel and oxygen from air. The flow pattern demonstrates the onset of Kelvin–Helmholtz instability on the interface between the main flow and the reacted gas. It is shown that an increase in the supplied fuel pressure leads to a decrease in the oscillation frequency and an increase in the characteristic size of oscillations.

中文翻译：

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超声速空腔通道内流动结构分析

摘要

给出了含空腔通道内超声速流动的数值研究结果。使用快速傅立叶变换对计算出的振荡谱进行分析。在所得的周期性自振荡区域中可以区分两种类型的振荡模式。第一类模式对应于声波沿腔体传播引起的声振动，并使用修正的罗西特公式计算。第二种模式对应于由腔体和外部流之间的质量传递引起的流量振荡的频率。结果表明，当燃料在腔体前面供给时，流动结构发生了变化。活跃燃烧发生在燃料和空气中氧气的混合层中。流动模式表明在主流和反应气体之间的界面上开始出现开尔文-亥姆霍兹不稳定性。结果表明，供给燃油压力的增加导致振荡频率的降低和振荡特征尺寸的增加。