Study on the recognition of aero-engine blade-casing rubbing fault based on the casing vibration acceleration

• A lot of blade-casing rubbing experiments are carried out.
• The rubbing characteristics are extracted from the casing acceleration signals.
• The rubbing fault have obvious cycle impact characteristics.
• The strength of impact is modulated by rotating frequency.
• The results are verified by using the an actual aero-engines’ test data.

By mean of the aero-engine rotor experiment rig with casings, the blade-casing rubbing experiments, which include the single-point rubbing and the partial rubbing, are carried out. The casing vibration acceleration signals are analyzed in order to extract the rubbing faults’ characteristics. The results show that: the casing signals under rubbing have obvious impact characteristics; the impact frequency is the frequency of blades passing the casing, and it equals the product of rotating frequency and the number of blades; in the frequency spectrum, there is the blades-passing frequency and its multiple-frequencies; the strength of impact is modulated by rotating frequency, so that there are families of side bands on both sides of the blades-passing 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. Finally, the rubbing characteristics found out in this paper are verified by using an actual aero-engines’ test data.