Numerical investigation on bristles buoyancy effect of brush seals with fluid-structure interaction

The bristles buoyancy effect of brush seal directly affect its sealing performance and service life. The theory of brush seal bristles buoyancy effect was analyzed, and the three-dimensional transient numerical model of brush seal bristles buoyancy effect was established using arbitrary Lagrange Euler (ALE) fluid-structure coupling method. Based on the accuracy of numerical model, the overall deformation characteristics of bristles were studied, and the axial, radial and total deformations of bristle tips were quantitatively analyzed. The effects of structural parameters and working parameters on bristles buoyancy effect of brush seal were studied, and the inducing mechanism of bristles buoyancy effect of brush seal was revealed. The research results showed that the bristles buoyancy effect of brush seal contributed to the disturbance of the front bristles caused by the unsteady radial airflow. The bristles buoyancy effect of brush seal can cause large deformation of the front bristles in the direction of the flow, generate radial clearance between the front plate and the rotor surface, and increase the leakage. When the inlet and outlet pressure ratio increased from 2 to 4, the average deformation of bristle tips increased by 47%, and the protection height of the front plate increased from 1.5 mm to 2.5 mm, and the average deformation of bristle tips increased by 36%, both of which enhanced the bristles buoyancy effect. The radial airflow channel was provided by the clearance between the front plate and the bristle pack, and the radial pressure gradient was generated by the inlet and outlet pressure difference in the clearance between the front plate and the bristle pack as the inducing condition of the bristles buoyancy effect. The bristles buoyancy effect can be reduced by increasing the diameter of the bristles and reducing the clearance between the front plate and the bristle pack. © 2024 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.