Flow instabilities in turbomachines

Instabilities occurring in systems involving the movement of a fluid through pipes, ducts, etc., by means of turbomachinery are discussed. While static instabilities may be inferred from system transient performance that is viewed as a sequence of quasi-steady states, such parameters as system interfaces and capacitances must be included in the prediction of dynamic instability, since they play an essential role in determining the transient response of the system to disturbances. A pumping system can be statically stable and still exhibit dynamic instability. Attention is given to rotating stall compressor instability, inlet distortion effects on axial compressor instability, the stability effects of downstream components, and the stability of centrifugal compressors and pumps.