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Investigation of high-speed rubbing behavior of labyrinth-honeycomb seal for turbine engine application

The labyrinth-honeycomb seal has been widely used in gas turbine engines as an abradable gas path seal to protect the rotor from wear and damage in rubbing interaction. It usually works with a stepped labyrinth because the knife-edged tips could produce a special dynamic sealing system, and then the minimum clearance is possible between the rotor and stationary component. To investigate the high-speed rubbing behavior between a Hastelloy-X honeycomb material and a GH4169 double stepped labyrinth, nine rubbing tests were conducted using a high-speed abrasion test rig while the blade tip speed varied from 150 to 450 m/s, and the incursion rate from 120 to 360 µm/s. The abradability of honeycomb made from Hastelloy-X was fully verified by analyzing the visual rubbing observations, rubbing forces, and impact acceleration. It is shown that compression deformation happens to the honeycomb material during the rubbing process with the labyrinth blade except for a simple cutting mechanism, which is mainly affected by the parameter of incursion rate. Thermal ablation and oxidation were the main damage occurring on the labyrinth tip and appeared more obviously at a higher blade tip speed. Rubbing forces and impact acceleration were obtained from a piezoelectric dynamometer and acceleration sensor during the rubbing process. At a blade tip speed of 300 m/s and incursion rate of 360 µm/s, radial and tangential forces show their maximum values of 716 N and 871 N, respectively. The peak value of acceleration presents 341g with the highest blade tip speed of 450 m/s and the highest incursion rate of 360 µm/s. All testing results provide a great deal of effective information on high-speed rubbing behavior for the abradablility evaluation of a honeycomb.