Abstract: Three-dimensional multi-passage numerical simulations were conducted to investigate the unsteady flow and its associated flow mechanism in a transonic compressor rotor at near stall conditions. The predicted results were compared with the available experimental data and a good agreement was achieved. The numerical monitoring results indicate that pressure disturbance appear at near stall flow conditions，which originate in the near-tip passages with higher amplitudes near the blade leading edge of the pressure side of the passage. With mass flow decreased，the amplitude of the disturbance and its active period increase. Further analyses of instantaneous flow fields show that a vortex structure，termed as tip secondary vortex，and its periodic oscillation lead to the appearance of the pressure disturbance. With mass flow decreased，the strength of TSV increases，thus leading to an increase in the disturbance's amplitude and its active period. Meanwhile，the near-tip flow blockage and "tip spillage flow" induced by TSV increase. As a result，the occurrence of TSV and the variation of its strength is a key factor which sets the stability limit of the investigated rotor.

Key words: Numerical simulation；Unsteady disturbance；Tip leakage vortex；Tip secondary vortex

摘要： 为了探究近失速工况下，跨声速压气机转子中非定常流动及相关流动机制，采用多通道全三维数值模拟方法对跨声速转子其内部流场进行了数值模拟，并利用已有的实验数据对计算结果进行了校核。对近失速工况探针监测结果的分析表明:流场中出现了非定常扰动，且扰动最活跃的区域位于近叶尖通道靠近叶片前缘的压力面侧；随着流量的降低，非定常扰动的幅值增大，波动周期变长。对近叶尖瞬态流场的分析表明:流场中的一个不同于泄漏涡的涡结构(命名为叶尖二次涡)的出现及其沿流向的发展诱发了非定常静压扰动，而且其强度随着流量的降低而增强，由此导致了非定常扰动的周期变长，振幅增加。伴随着叶尖二次涡强度的增加，叶顶通道的阻塞以及由叶尖二次涡诱发的“前缘溢流”也随之增强。因此，叶尖二次涡的出现及其强度的变化是影响该跨声速转子流动稳定性的主要因素之一。

关键词: 数值模拟；非定常扰动；泄漏涡；叶尖二次涡