Characteristics analysis of blade-casing rubbing based on casing vibration acceleration

Blade-casing rubbing experiments, which include single-point rubbing and partial rubbing, are carried out on an aero engine rotor experimental rig with casings. Casing vibration acceleration signals are analyzed for extracting the rubbing faults' characteristics. The results show that under rubbing, casing signals have obvious impact characteristics: impact frequency is the frequency of blades passing the casing, and it equals the product of rotating frequency and the number of blades; the frequency spectrum shows the blade-passage frequency and its multiple-frequencies; impact strength is modulated by the rotating frequency so that there are families of side bands on both sides of the blade-passage frequency and its multiple frequencies, and the side bands' interval equals the rotating frequency. There are obvious quefrency components of the rotating frequency and its multiple frequencies in the cepstrum, and there is also a distinct rotating frequency and its multiple frequencies in the wavelet envelope spectrum. Finally, the rubbing characteristics determined in this study are verified by using test data from an actual aero engine.