The right figure summarizes the analysis results of 10 different vibration measurement points on an aero-engine gas turbine. The 124Hz frequency corresponding to the low-pressure rotor is found at points 1, 3, 4, and 5, but it is not a main contributor to the amplitude. The 210Hz frequency corresponding to the high-pressure rotor is detected at all 10 measurement points, and it is a main amplitude contributor for most of them.
Additionally, the sidebands of 210Hz—157Hz and 264Hz—are found at points 1, 3, 4, 5, 7, 8, and 10. The modulation frequency of 54Hz and its second harmonic are detected at point 6. Therefore, it is suspected that the cause of the sidebands in the high-pressure rotor may be related to an abnormal structure near point 6.
Finally, the second harmonic of the high-pressure rotor frequency (210Hz) is simultaneously observed at points 2, 7, 8, and 9, though their amplitude contributions are minor.
