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Aero-acoustic performance of a continuous transonic wind-tunnel axial-flow compressor

A three-stage axial-flow compressor was developed for a continuous transonic wind tunnel. The rotor-stator spacing and the ratio of number of rotor blades to number of stator vanes were properly chosen for the purpose of aero-acoustic noise suppression. The aero-acoustic performances of the axial-flow compressor were tested and analyzed. The test results show that the first BPF tonal noise is effectively suppressed even though some of it still exists; the noise amplitude frequency spectrum shows that the abnormal tonal noise, which is different from that related to BPF and its harmonics, exists under a wide range of working conditions and plays a dominant role in determining the sound pressure levels of the inlet and outlet of the axial-flow compressor. The comparison of test results shows that vibration is induced by the periodic non-uniform inlet flow condition and that the rotor blade that has a high aspect ratio is one of the main noise sources responsible for the abnormal tonal noise.