Conceptual Flutter Analysis of Stepped Labyrinth Seals

  1. Corral, Roque 1
  2. Greco, Michele 2
  3. Vega, Almudena 2
  1. 1 Advanced Engineering Direction, Industria de Turbopropulsores S.A.U., Madrid
  2. 2 Universidad Politécnica de Madrid
    info

    Universidad Politécnica de Madrid

    Madrid, España

    ROR https://ror.org/03n6nwv02

Revista:
Journal of Engineering for Gas Turbines and Power

ISSN: 0742-4795,  1528-8919

Año de publicación: 2020

Volumen: 142

Número: 7

Tipo: Artículo

DOI: 10.1115/1.4046419 GOOGLE SCHOLAR lock_openAcceso abierto editor

Otras publicaciones en: Journal of Engineering for Gas Turbines and Power

Resumen

A simple nondimensional model to describe the flutter onset of two-fin straight labyrinth seals (Corral and Vega, 2018, “Conceptual Flutter Analysis of Labyrinth Seals Using Analytical Models—Part I: Theoretical Background,” ASME J. Turbomach., 140(10), p. 121006) is extended to stepped seals. The effect of the axial displacement of the seal is analyzed first in isolation. It is shown that this fundamental mode is always stable. In a second step, the combination of axial and torsion displacements is used to determine the damping of modes with arbitrary torsion centers. It is concluded that the classical Abbot's criterion stating that seals supported on the low-pressure side of the seal are stable provided that natural frequency of the mode is greater than the acoustic frequency breaks down under certain conditions. An analytical expression for the nondimensional work-per-cycle is derived and new nondimensional parameters controlling the seal stability identified. It is finally concluded that the stability of stepped seals can be assimilated to that of a straight through seal if the appropriate distance of the torsion center to the seal is chosen.

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