Study of a New Method for Giving Warning Signals of Instability

A new method has been developed to give early warning signals just before a compressor runs into instability. Analyses based on prestall pressure signals of several axial compressors reveal that the dynamic pressure energy accumulation in a compressor just before the instability could be used as a precursor signature of the instability.It is illustrated that by using the appropriate RMS of the casing static pressure over the rotor tip an early warning could be obtained about 1～2 seconds before the onset of the instability.This is particularly important because the method is applicable to the spike type stall inceptions as well as the model type ones,the former usually appears abruptly and does not have a precursor.