中心线偏置隔离段内激波串振荡特性

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. 

Oscillation characteristics of shock train in deflected center-line isolator

An investigation was conducted on the oscillation characteristics of shock train in deflected center-line isolator by using unsteady numerical simulation methods. The effects of back-pressure of isolator exit and expanded ratio of isolator on the oscillation characteristics of shock train were analyzed. The results show that the peak exit total pressure corresponds to the smallest displacement of the shock train leading edge and the valley exit total pressure corresponds to the largest displacement. The further research indicates that the self-excited oscillation of shock train in isolator only occurs under several back-pressure conditions and the shock train keeps steady under high back-pressure finally. Compared with the straight isolator, the shock train self-excited oscillation is prone to occur in deflected center-line isolator under the same incoming flow Mach number of 2.0. In addition, under the same back-pressure condition, the larger expanded ratio(eg.37%) means the lower oscillation frequency, amplitude and time-mean exit total pressure the flow field can be got when the self-excited oscillation phenomena occurs.