Experimental Investigation on the Rubbing Process of Labyrinth Seals Against Honeycomb Liners

Sealing systems contribute significantly to the efficiency of turbomachinery. Small gap widths, which are important for low leakage mass flows in labyrinth seals, combined with thermal and mechanical expansion of the rotor can lead to contact with the stator. During these so-called rubbing processes, it is necessary to make an accurate prediction with respect to the performance and service life of the seal. For this purpose, the influence of relative velocity in the contact (up to 165ms−1) and incursion rate (up to 0.5 mms−1) on the resulting thermal and mechanical loads as well as wear mechanisms are studied for the rubbing process between an inclined labyrinth seal fin and a honeycomb segment. Furthermore, different axial configurations of the seal fin with respect to the honeycomb structure are considered. The system reacts very sensitively to a change of the seal fin position relative to the honeycomb structure. The incursion per revolution reflects a change of the wear mechanism from abrasive to plastic for a certain value. The results of this study contribute to the optimization of labyrinth seals and the development of new types of liner materials as well as geometries.