Performance of centrifugal compressor in surge

When the flow of centrifugal compressor is reduced to a certain value, surge will occur. When centrifugal compressor surge, there are generally the following external phenomena: pulsation of air flow and strong noise; The pressure drops suddenly and is very unstable; The high-pressure gas after the stage or after the compressor flows back to the working wheel; The compressor has strong vibration, and even the vibration of the whole device will be caused when the surge is serious.