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为了解隔离段在真实燃烧室反压作用下的工作特性,通过数值方法模拟燃烧室振荡燃烧引起的脉动反压,在来流Mai=2条件下,探讨了脉动反压引起的激波串受迫振荡特性。结果表明,在反压脉动条件下,激波串前缘位置周期振荡,其振荡频率与反压脉动频率一致,振幅与反压脉动频率负相关,反压脉动频率600Hz时,振幅仅为管道长2.97%;就抗反压能力而言,在反压脉动条件下,隔离段能承受比定常状态更大的反压峰值,且脉动频率越大,可承受瞬态反压峰值越大。激波串的受迫振荡包含两种形式:激波串整体位置的前后运动和激波节之间的相对运动。在一定程度内,反压脉动频率较低时(50Hz,100Hz),激波串整体位置的前后运动是主要的受迫振荡形式,激波节之间的相对运动很弱;随反压脉动频率升高(300Hz,600Hz),激波节之间的相对运动加剧,逐渐成为激波串受迫振荡的主要形式。另外,在激波串振荡过程中,激波串往上下游运动经过同一位置时,激波串形态会出现迟滞,这是导致总压恢复系数迟滞的原因。
In order to understand the operating characteristics of the isolation section under the action of backpressure in the real combustion chamber, the pulsating backpressure caused by the oscillation combustion in the combustion chamber was numerically simulated. Under the condition of the flow of Mai = 2, Forced oscillation characteristics. The results show that under the conditions of back pressure pulsation, the leading edge of the shock wave oscillates periodically and its oscillation frequency is consistent with the back pressure pulsation frequency. The amplitude is negatively correlated with the back pressure pulsation frequency. When the back pressure pulsation frequency is 600 Hz, the amplitude is only the pipe length 2.97%. With respect to anti-back pressure capability, under the condition of back pressure pulsation, the isolation section can withstand larger backpressure peak than the steady state, and the larger the ripple frequency, the larger the transient backpressure peak. The forced oscillations of a shock train consist of two forms: the anteroposterior movement of the shock train in its entirety and the relative movement of the shock knuckles. To a certain extent, the back-and-forth motion of shock train is the main form of forced oscillation when the back-pressure pulsation frequency is low (50Hz, 100Hz), and the relative motion between shocks is weak. (300Hz, 600Hz), the relative motion between shock knuckles aggravate and gradually become the main form of forced oscillation of shockwaves. In addition, during the oscillation of the shock wave train, the shock wave train will appear in hysteresis when the shock wave train passes the same position up and down, which is the cause of the hysteresis of the total pressure recovery coefficient.