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.
Highlights
Annular gas seals in turbomachinery are widely used to minimize the leakage rate through clearance involved with rotating and stationary parts [1]
5, one part of gas directly goes through seal clearance and the other part a big vortex as ainresult rotor high speed rotation and pressure difference between theforms inlet and a big vortex as a result of rotor high speed rotation and pressure difference between the inlet and the the outlet
Numerous seal holes in the stator surface lead to a large reduction of gas forward speed, which which is promising for reducing leakage rates of hole-pattern damper seals
Summary
Annular gas seals in turbomachinery are widely used to minimize the leakage rate through clearance involved with rotating and stationary parts [1]. The design of advanced turbomachinery requires higher speed, tighter clearance, and higher thrust to weight ratio. In this situation, rotor instability has become more critical due to the reaction force in annular gas seals [3]. Rotor instability has become more critical due to the reaction force in annular gas seals [3] Damper seals such as honeycomb and hole-pattern seals are attractive from a rotor-dynamic standpoint since they tend to have higher effective damping, and a better leakage rate control than see-through labyrinth seals [4]. Numerous investigations have found that the labyrinth seals in Materials 2019, 12, 2324; doi:10.3390/ma12142324 www.mdpi.com/journal/materials
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