Numerical Investigation on Static and Rotor-Dynamic Characteristics of Convergent-Tapered and Divergent-Tapered Hole-Pattern Gas Damper Seals

Abstract

To study the influence of taper seal clearance on the static and rotor-dynamic characteristics of hole-pattern damper seals, this paper develops three-dimensional transient computational fluid dynamic methods, which comprise single-frequency and multi-frequency elliptical orbit whirl model, by the transient solution combined with a mesh deformation technique. Through the investigations, it is illustrated that: (1) In the present paper, the leakage rates of convergent-tapered hole-pattern damper seals are less than divergent-tapered hole-pattern damper seals for the same average seal clearance, and the maximum relative variation reaches 16%; (2) Compared with a constant clearance hole-pattern damper seal, the maximum relative variation of the rotor-dynamic coefficients is 1,865% for nine taper degrees in this paper; (3) Convergent-tapered hole-pattern damper seals have smaller reaction forces and effective damping coefficient, larger cross-over frequency, and direct stiffness coefficient, while divergent-tapered damper seals have the opposite effects; (4) Divergent-tapered hole-pattern damper seals alleviate the rotor whirl because of a larger effective damping coefficient when the rotor system has large natural frequency and small eccentricity. Convergent-tapered damper seals provide both sealing and journal bearing capabilities at the same time, and are more advantageous to the stability of the rotor system when rotor eccentricity is the main cause of rotor instability.

Vibration Attenuation Mechanism of the Rotor System with Anisotropic Support Stiffness

“…The rotor system is a core component of rotating machinery. The design of robust rotor dynamics can significantly improve the working efficiency of rotating machinery and reduce unit vibration levels [1,2]. Currently, rotating machinery requires higher speeds and tighter clearances due to increased thermal efficiency and power demand.…”

“…S. Li, L. Zheng System with Anisotropic Support Stiffness (2) The bearing damping not only the amplitude of backward whirl, but also reduces the spin speed range of backward whirl. Therefore, for the rotor system with anisotropic supports, the high cycle fatigue of the shaft and the rotor instability caused by internal damping of shaft material can be alleviated by increasing the bearing damping.…”