Surge in compressors

Compressor surge is a form of aerodynamic instability in axial compressors or centrifugal compressors. The term describes violent air flow oscillating in the axial direction of a compressor, which indicates the axial component of fluid velocity varies periodically and may even become negative. In early literature, the phenomenon of compressor surge was identified by audible thumping and honking at frequencies as low as 1 Hertz, pressure pulsations throughout the machine, and severe mechanical vibration.