0
Research Papers: Other (Seals, Manufacturing)

A Numerical Study of Labyrinth Seal Flutter

[+] Author and Article Information
L. di Mare, M. Imregun

Department of Mechanical Engineering, Vibration UTC, Imperial College London, London SW7 2AZ, UK

J. S. Green

 Rolls-Royce plc, P.O. Box 31, Derby DE24 8BJ, UK

A. I. Sayma

Department of Engineering and Design, University of Sussex, Brighton BN1 9QT, UK

J. Tribol 132(2), 022201 (Apr 06, 2010) (7 pages) doi:10.1115/1.3204774 History: Received December 14, 2006; Revised July 20, 2009; Published April 06, 2010; Online April 06, 2010

A numerical study of a labyrinth-type turbine seal flutter in a large turbofan engine is described. The flutter analysis was conducted using a coupled fluid-structure interaction code, which was originally developed for turbomachinery blade applications. The flow model is based on an unstructured, implicit Reynolds-averaged Navier–Stokes solver. The solver is coupled to a modal model for the structure obtained from a standard structural finite element code. During the aeroelasticity computations, the aerodynamic grid is moved at each time step to follow the structural motion, which is due to unsteady aerodynamic forces applied onto the structure by the fluid. Such an integrated time-domain approach allows the direct computation of aeroelastic time histories from which the aerodynamic damping, and hence, the flutter stability, can be determined. Two different configurations of a large-diameter aeroengine labyrinth seal were studied. The first configuration is the initial design with four fins, which exhibited flutter instability during testing. The second configuration is a modified design with three fins and a stiffened ring. The steady-state flow was computed for both configurations, and good agreement was reached with available reference data. An aeroelasticity analysis was conducted next for both configurations, and the model was able to predict the observed flutter behavior in both cases. A flutter mechanism is proposed, based on the matching of the structural frequencies to the frequencies of waves traveling in the fluid, in the interfin cavities and in the high- and low-pressure cavities.

FIGURES IN THIS ARTICLE
<>
Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Schematic of 4-fin seal

Grahic Jump Location
Figure 2

Schematic of 3-fin seal, showing machined-away fin and stiffening ring

Grahic Jump Location
Figure 3

Views of the computational grid—4-fin configuration

Grahic Jump Location
Figure 4

Predicted relative Mach number contours from steady-state flow analysis at nominal pressure ratio and seal gaps of (a) 0.35 mm, (b) 0.50 mm, and (c) 0.65 mm—4-fin configuration

Grahic Jump Location
Figure 5

Predicted streamlines in the meridional plane for nominal pressure ratio and 0.50 mm gap—4-fin configuration

Grahic Jump Location
Figure 10

Variation in aerodamping with nodal diameter number

Grahic Jump Location
Figure 6

Seal characteristics—4-fin configuration

Grahic Jump Location
Figure 7

Predicted relative Mach number contours at nominal pressure ratio and 0.50 mm seal gap—3-fin configuration

Grahic Jump Location
Figure 8

Computed streamlines in the meridional plane at nominal pressure ratio and 0.50 mm seal gap—3-fin configuration

Grahic Jump Location
Figure 9

Structural model—4-fin configuration

Grahic Jump Location
Figure 11

Variation in contributions to the work done from each surface on the seal rotor with nodal diameter—4-fin configuration

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In