Basic Nature of Behaviors of Surge Frequencies in Multi-Stage Axial Flow Compressors

Abstract

The behaviors of surge frequencies in multi-stage axial-flow compressors are studied by use of several non-dimensional parameters on the basis of numerical-experimental results. One of the essential parameters proves to be a flowpath-average reduced surge frequency multiplied by the stalling pressure ratio and the tip-Mach number. Framework map in terms of such parameters against reduced resonance frequencies can provide a whole view of the surge frequency behaviors, including various characteristic zones of surge behaviors, i.e., convective surges, near-resonant surges, degenerated surges, and multi-stage effects. Particularly, for the convective surges, the surge frequency parameter comes to have a nearly constant value over a wide range of the reduced resonance frequencies, independently of number of stages, speeds, and pressure ratios, etc., of the compressors. The map is practically useful for the evaluation of deep-surge frequencies. At the same time, it could form a base for further investigations into the surge phenomena.