Centrifugal Compressors

Centrifugal compressors generate spectra similar to centrifugal fans in that the vane pass frequency will be dominant. Damaged or eroded vanes will cause increases in the level at the vane pass, and also will usually produce 1X sidebands around the vane pass. Compressor surge is a fluid dynamic problem at the compressor output port that usually causes vibration at less than 1X frequency. It is often caused by improper output pressure.

Below is a typical vibration spectrum from a 6-vaned centrifugal compressor.

Vane Pass Harmonics