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.

1.
Munson
,
J.
, and
Pecht
,
G.
, 1992, “
Development of Film Riding Face Seals for a Gas Turbine Engine
,”
Tribol. Trans.
1040-2004,
35
(
1
), pp.
65
70
.
2.
Alford
,
J. S.
, 1964, “
Protection of Labyrinth Seals From Flexural Vibration
,”
J. Eng. Power
0022-0825,
86
(
April
), pp.
141
148
.
3.
Lewis
,
D. A.
,
Platt
,
C. E.
, and
Smith
,
B. E.
, 1979, “
Aeroelastic Instability in F100 Labyrinth Air Seal
,”
J. Aircr.
0021-8669,
16
(
7
), pp.
484
490
.
4.
Abbott
,
D. R.
, 1980, “
Advances in Labyrinth Seal Aeroelastic Instability Prediction and Prevention
,” ASME Paper No. 80-GT-151.
5.
Rhode
,
D. L.
,
Hensel
,
S. J.
, and
Guidy
,
M. J.
, 1993, “
Three-Dimensional Computations of Rotordynamic Force Distribution in a Labyrinth Seal
,”
Tribol. Trans.
1040-2004,
36
(
3
), pp.
461
469
.
6.
Ishii
,
E.
,
Kato
,
C.
,
Kikuchi
,
K.
, and
Ueyama
,
Y.
, 1997, “
Prediction of Rotordynamic Forces in a Labyrinth Seal Based on Three-Dimensional Turbulent Flow Computations
,”
JSME Int. J., Ser. C
1340-8062,
40
(
4
), pp.
743
748
.
7.
Kwanka
,
K.
,
Sobotzik
,
J.
, and
Nordman
,
R.
, 2000 “
Dynamic Coefficients of Labyrinth Gas Seals, A Comparison of Experimental Results and Numerical Calculations
,” ASME Paper No. 2000-GT-403.
8.
Hirano
,
T.
,
Guo
,
Z.
, and
Kirk
,
R. G.
, 2005, “
Application of CFD Analysis for Rotating Machinery—Part 2: Labyrinth Seal
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
127
(
4
), pp.
820
826
.
9.
Sayma
,
A. I.
,
Breard
,
C.
,
Vahdati
,
M.
, and
Imregun
,
M.
, 2002, “
Aeroelasticity Analysis of Air-Riding Seals for Aeroengine Applications
,”
ASME J. Tribol.
0742-4787,
124
(
3
), pp.
607
616
.
10.
Baldwin
,
B. S.
, and
Barth
,
T. J.
, 1991, “
A One Equation Turbulence Transport Model for High Reynolds Number Wall Bounded Flows
,” AIAA Paper No. 91-0610.
11.
Sayma
,
A. I.
,
Vahdati
,
M.
, and
Imregun
,
M.
, 2000, “
An Integrated Non-Linear Approach for Turbomachinery Forced Response Prediction. Part I: Formulation
,”
J. Fluids Struct.
0889-9746,
14
(
1
), pp.
87
101
.
12.
Swanson
,
R. C.
, and
Turkel
,
E.
, 1992, “
On Central Difference and Upwind Schemes
,”
J. Comput. Phys.
0021-9991,
101
, pp.
292
306
.
13.
Jorgenson
,
P. C.
, and
Turkel
,
E.
, 1993, “
Central Difference TVD Schemes for Time Dependent and Steady State Problems
,”
J. Comput. Phys.
0021-9991,
107
, pp.
297
308
.
14.
Roe
,
P.
, 1981, “
Approximate Riemann Solvers, Parameter Vectors and Difference Schemes
,”
J. Comput. Phys.
0021-9991,
43
, pp.
357
384
.
15.
Batina
,
T. J.
, 1989, “
Unsteady Euler Algorithm With Unstructured Dynamic Mesh for Complex Aircraft Analysis
,” AIAA Paper No. 89-1189.
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