Buoyancy Effect of Bristles for a Brush Seal with Disturbance-Suppressing Holes

Abstract

Bristles in the first few rows float up from the rotor surface due to the radial airflow in the gap between the front plate and bristle pack, which directly affects seal performance and the service life of a brush seal. In this paper, firstly, two three-dimensional transient calculation models for a traditional brush seal (TBS) and a brush seal with disturbance-suppressing holes (DSBS) are established, respectively, based on the arbitrary Lagrange–Eulerian (ALE) method to study bristle deformation characteristics and leakage flow characteristics of the seals. Furthermore, effects of disturbance-suppressing (DS) hole structural parameters (i.e., height, diameter, and number of hole rows) were investigated to reveal the suppression mechanism of the DS holes on the buoyancy effect of bristles. The results showed that as soon as free ends of bristles at the first few rows moved along direction of the front plate in response to the radial airflow from the gap between front plate and bristle pack, a buoyancy effect of bristles occurred. The DSBS with DS holes set in the front plate of the TBS had a lower deformation of the bristles and a lower leakage amount of seal compared with that of TBS, indicating a good suppression to the buoyancy effect. With decreasing hole height and increasing hole diameter and number of hole rows, the suppression of bristle disturbance gradually increased due to decreases of the radial airflow and increases of torque acting on the bristles.