Abstract: In order to analyze the noise characteristic of a single-stage low-speed axial compressor under various working condition， the upstream propagating noise was measured by an in-duct sensory array which consisted of 20 equally spaced microphones. Then the spectrum was obtained. The circumferential modal amplitudes were calculated by utilizing mode detection technique. The experimental results were compared with Tyler and Sofrin’s duct mode theory. According to the result， it can be noted that the sound pressure level of the noise at first and second blade passing frequency (BPF) was very high. However， this kind of noise was thought to be cut-off according to Tyler and Sofrin’s theory. Sound modal analysis revealed that new generation mechanisms of sound mode at 1BPF and 2BPF are exist in these low-speed compressors.

Key words: Low-speed axial compressor；Microphone array；Spectrum；Acoustic mode；Blade passing frequency

摘要： 为研究单级低速轴流压气机的噪声特性，在压气机进气道的壁面上，采用由20路传声器组成的周向均布阵列对其前传噪声信号进行测量，获取频谱特性及周向模态特性，并将实验测得的结果与理论预测的结果进行对比分析。实验结果显示，在Tyler-Sofrin转静干涉理论上不存在可传播声模态的1倍和2倍叶片通过频率下，却检测到明显的信号峰值。进一步分析模态分解结果后发现，在这类低速轴流压气机的1倍和2倍叶片通过频率下存在其它的声模态产生机制。

关键词: 低速轴流压气机；传声器阵列；频谱；声模态；叶片通过频率