Numerical simulation of deformation hysteresis effect of the bristles of brush seals

Abstract

Because of their good sealing performance, brush seals are used widely in turbomachinery as alternatives to traditional labyrinth seals. However, obstructed by friction, the flexible bristles cannot recover fully after deformation, resulting in a hysteresis effect and decreased sealing performance. In the present study, a three-dimensional multi-row bristle model is established that considers the friction between the neighbouring bristles and back plate. Then the deformation and recovery of the bristles during the radial reciprocating offset of the rotor in the presence of a pressure difference are studied. To evaluate the hysteresis effect, analysis is directed at the unrecovered bristle deformation in the radial direction affected by bristle diameter, bristle lay angle, fence height and width of pressure relief chamber. The results show that the larger the bristle diameter and fence height, the weaker the hysteresis effect and the larger the bristle lay angle, the stronger the hysteresis effect. With increasing width of the pressure relief chamber, the hysteresis effect weakens and then strengthens, meaning that the pressure relief chamber has an optimal axial width that departure from enhances the hysteresis effect. The present results offer a reference for selecting the structural parameters of brush seals in engineering design.