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采用非定常数值方法研究了一种中心线偏置隔离段内的激波串振荡特性,分析了隔离段出口反压及管道扩张比对激波串振荡特性的影响规律.结果表明:出口总压最大值对应激波串前缘最小位移,出口总压最小值对应激波串前缘最大位移.在一定大小反压条件下隔离段内出现激波串的自激振荡,在较高反压条件下激波串稳定在管道内部.在来流马赫数为2.0条件下,中心线偏置隔离段较等直隔离段更易出现激波串自激振荡.在出现激波串自激振荡时,在同一反压条件下,大扩张比(如37%)隔离段流场的振荡主频、幅度和出口平均总压均小于小扩张比隔离段.
The unsteady numerical method was used to study the oscillation characteristics of a shock wave string in a centerline offset isolation section. The influence of the backpressure at the exit of the isolation section and the pipe expansion ratio on the oscillation characteristics of the shock train was analyzed. The maximum value corresponds to the minimum displacement of the leading edge of the shockwave and the minimum value of the total outlet pressure corresponds to the maximum displacement of the leading edge of the shockwave.The spontaneous oscillation of the shockwave occurs in the isolated section under a certain size of backpressure, The next shock wave train is stable in the pipeline.When the flow Mach number is 2.0, the centerline offset isolation segment is more likely to appear self-oscillating shock wave than the iso-isolating segment.When shock wave self-oscillation occurs, Under the same backpressure condition, the dominant frequency, amplitude and average exit pressure of the flow field in the large expansion ratio (eg, 37%) are smaller than that of the small expansion ratio.