Vibrations Induced by Rubbing Between Labyrinth and Rubber-Coating for Rotating Engine in Experiment

Rotor-stator rubbing is common in rotating engines, and the induced vibrational characteristics of the rotor and stator are affected by the rubbing materials. The soft coating made by vulcanized rubber is considered for rubbing case, followed by the experimental investigations on the kind of progressive rubbing between the seal-labyrinth and the seal-case of a rotor. The vibrational waveforms and the spectral features of the rotor and stator, together with the shaft orbits during the rubbing process are analyzed. The center of the rotor is forced to shift from the balance point of zero displacement, in the meanwhile, the vibrational acceleration of the stator is increased radically and finally nonlinear instability is excited during the rubbing. The shaft orbit varies from stable to unstable, and recovers to be stable eventually. Rotor-stator coupling resonance is captured both in the rotor and stator vibrational signals. High-order super-harmonics (corresponding to the resonance of the rotor and stator), the modulations of the fundamental rotating frequency are excited by the soft rubbing.