轴流压气机近失速状态叶片通过频率特性研究

Investigation on the characteristics of blade passing frequency of axial flow compressor at near stall conditions

关键词:  轴流式压气机  失速  静压  时频分析  气动稳定性

Key words:  Axial flow compressor  Stalling  Static pressure  Time-frequency analysis  Aerodynamic stability

摘要:

为研究压气机转子叶片通过频率特性与压气机气动稳定性之间的内在联系,对某型单轴涡喷发动机的轴流式压气机静子机匣壁面静压信号进行了时频分析。结果表明,发动机运行过程中压气机叶片通过频率特性的变化可以反映特定的压气机级的流态变化。在中小转速的工况下,随着发动机工作点逐渐靠向喘振边界,机匣壁面静压信号中压气机第1级至第3级转子的叶片通过频率信号逐渐增强。与设计点相比,在近失速边界的工况下,压气机第1级转子叶片通过频率幅度增强达10dB以上。此外,在中低转速范围内打开放气带后,压气机前面级转子叶片通过频率幅度显著减小,与流场的变化情况相一致。因此,轴流压气机转子叶片通过频率特性可以提供压气机气动稳定工作状况的重要信息。

Abstract:

To investigate the internal relationship between blade passing frequency (BPF) characteristics of compressor rotors and aerodynamic stability of corresponding compressor, time-frequency analysis was performed to analyze stator casing wall static pressure of axial flow compressor of a certain single-spool turbojet engine. Data processing results show that the variation of compressor rotor BPF characteristics during engine operation can reflect flow regime transients of a specific compressor stage. As engine operating point gradually approaches the surge line at part-speed operation, compressor rotor BPF magnitudes of casing wall static pressure of the first three compressor stages gradually increase. As compared with design point, the BPF magnitude of the first compressor rotor gets an augmentation of more than 10 dB at near stall conditions. Moreover, the BPF magnitudes of the front compressor stages decrease notably as the bleed valve is opened at part-speed, which is consistent with the improvement of flow field induced by the bleeding. Thus, BPF characteristics of axial flow compressor rotors are capable of providing important information about compressor aerodynamic stability.