Experimental Investigation for Rubbing-Induced Rotor-Stator Coupled Vibration of Thin-Walled Labyrinth Seal Systems

This paper presents experimental results on the rotor-stator rubbing-impact behavior of the labyrinth seal system. The objective of the work is to reveal the response characteristics and rotor-stator coupled resonance excitation conditions of thin-walled structures. A test rig consisting of a thin-walled drum rotor with a seal fin and a matching thin-walled drum stator was developed. Rubbing tests under various scenarios were performed when rotor operated near the coupled resonance speed. Time-domain vibration responses were recorded and both amplitude characteristics and spectral features were analyzed. The results indicate that no experimental evidence is found to support the occurrence of rotor–stator coupled resonance under partial rubbing conditions induced by rotor unbalance. Under these conditions, the vibration response spectrum contains contributions from multiple nodal-diameter mode vibrations. In contrast, partial rubbing induced by forced resonance of the stator can reliably initiates the coupled resonance. During resonance, the vibration amplitude increases significantly, and the response spectrum is dominated by the nodal diameter mode associated with the coupled resonance speed.