Leakage and rotordynamic characteristics of the bionic fish-scale-like hole-pattern damping seal

A well-designed hole cavity can enhance the performance of hole-pattern damping seals (HPDS). An interwoven fish scale pattern reduces flow resistance, and this study reverses the fish scale de-sign to develop a damping seal structure with a fish-scale-like perforated pattern. This approach enhances the steady-state and rotordynamic performance of hole-pattern damping seals. This work examines hole-pattern damping seal characteristics using transient moving mesh numerical simulations with ANSYS CFX, the elliptical whirl model, and an experimental platform. It compares the leakage control and rotordynamic stability of honeycomb (H-HPDS), circular (C-HPDS), and fish-scale-like (F-HPDS) damping seals. The study found that sparsely distributed large fish-scale apertures ( η = 1.0) and densely distributed small apertures ( η = 0.6) significantly increase fluid resistance and reduce leakage rates by 12–14% compared to conventional damping seal configurations. Turbulent double vortices and exit throttle contraction effects occur due to the fish-scale hole cavity's sloped flow-directing impact and sharp exit angle. These events in-crease fluid energy dissipation and reduce leakage. The porous F-HPDS seal with η = 1.0 outperforms the standard H-HPDS in stiffness coefficient while maintaining damping qualities. Without requiring any auxiliary devices, the F-HPDS seal achieves highly efficient inlet whirl compensation through the axial flow guidance of the fish-scale hole exit angles and the thorough mixing of high-velocity jets with the mainstream whirling flow. At 7500 rpm, its average effective stiffness increases by 122%. The inertial effects of the slanted jet at the fish-scale hole exit and the intensified circumferentially non-uniform pressure distribution create a pronounced local rotordynamic pressure zone on one side of the hole cavity. This enhances the seal's Lomakin effect and generates an aerodynamic force that counteracts rotor eccentricity, minimizes rotor displacement, and significantly boosts seal stiffness. This study demonstrates that innovative geometric design can substantially improve turbomachinery sealing performance.