The amount of cooling air assigned to seal high pressure turbine (HPT) rim cavities is critical for performance as well as component life. Insufficient air leads to excessive hot annulus gas ingestion and its penetration deep into the cavity compromising disk or cover plate life. Excessive purge air, on the other hand, adversely affects performance. Experiments on a rotating turbine stage rig which included a rotor–stator forward disk cavity were performed at Arizona State University (ASU). The turbine rig has 22 vanes and 28 blades, while the cavity is composed of a single-tooth lab seal and a rim platform overlap seal. Time-averaged static pressures were measured in the gas path and the cavity, while mainstream gas ingestion into the cavity was determined by measuring the concentration distribution of tracer gas (carbon dioxide) under a range of purge flows from 0.435% (Cw = 1540) to 1.74% (Cw = 6161). Additionally, particle image velocimetry (PIV) was used to measure fluid velocity inside the cavity between the lab seal and the rim seal. The data from the experiments were compared to time-dependent computational fluid dynamics (CFD) simulations using fluent CFD software. The CFD simulations brought to light the unsteadiness present in the flow during the experiment which the slower response data did not fully capture. An unsteady Reynolds averaged Navier–Stokes (RANS), 360-deg CFD model of the complete turbine stage was employed in order to increase the understanding of the swirl physics which dominate cavity flows and better predict rim seal ingestion. Although the rotor–stator cavity is geometrically axisymmetric, it was found that the interaction between swirling flows in the cavity and swirling flows in the gas path create nonperiodic/time-dependent unstable flow patterns which at the present are not accurately modeled by a 360 deg full stage unsteady analysis. At low purge flow conditions, the vortices that form inside the cavities are greatly influenced by mainstream ingestion. Conversely at high purge flow conditions the vortices are influenced by the purge flow, therefore ingestion is minimized. The paper also discusses details of meshing, convergence of time-dependent CFD simulations, and recommendations for future simulations in a rotor–stator disk cavity such as assessing the observed unsteadiness in the frequency domain in order to identify any critical frequencies driving the system.

References

References
1.
Ekman
,
V. W.
,
1905
, “
On the Influence of the Earth's Rotation on Ocean-Currents
,”
Arkiv. Mat. Astron. Fys.
,
2
(
11
), pp.
1
52
.
2.
Von Kármán
,
T.
,
1921
, “
Uber Laminare und Turbulente Reibung
,”
Z. Angew. Math. Mech.
,
1
(4), pp.
233
252
.10.1002/zamm.19210010401
3.
Batchelor
,
G. K.
,
1951
, “
Note on a Class of Solutions of the Navier–Stokes Equations Representing Steady Rotationally-Symmetric Flow
,”
Q. J. Mech. Appl. Math.
,
4
(
1
), pp.
29
41
.10.1093/qjmam/4.1.29
4.
Mellor
,
G. L.
,
Chapple
,
P. J.
, and
Stokes
,
V. K.
,
1968
, “
On the Flow Between a Rotating and a Stationary Disc
,”
J. Fluid Mech.
,
31
(
1
), pp.
95
112
.10.1017/S0022112068000054
5.
Daily
,
J. W.
, and
Nece
,
R. E.
,
1960
, “
Chamber Dimension Effects on Induced Flow and Frictional Resistance of Enclosed Rotating Discs
,”
ASME J. Basic Eng.
,
82
(1), pp.
217
–230.10.1115/1.3662532
6.
Bayley
,
F. J.
, and
Owen
,
J. M.
,
1970
, “
The Fluid Dynamics of a Shrouded Disc System With a Radial Outflow of Coolant
,”
ASME J. Eng. Power
,
92
(
3
), pp.
335
–341.10.1115/1.3445358
7.
Phadke
,
U. P.
, and
Owen
,
J. M.
,
1988
, “
Aerodynamic Aspects of the Sealing of Gas Turbine Rotor–Stator Systems, Part 1: The Behavior of Simple Shrouded Rotating-Disc Systems in a Quiescent Environment
,”
Int. J. Heat Fluid Flow
,
9
(2), pp.
98
105
.10.1016/0142-727X(88)90060-4
8.
Mirzamoghadam
,
A. V.
,
Heitland
,
G.
, and
Molla-Hosseini
,
K.
,
2009
, “
The Effect of Annulus Performance Parameters on Rotor–Stator Cavity Sealing Flow
,”
ASME
Paper No. GT2009-59380. 10.1115/GT2009-59380
9.
Phadke
,
U. P.
, and
Owen
,
J. M.
,
1988
, “
Aerodynamic Aspects of the Sealing of Gas Turbine Rotor–Stator Systems, Part 2: The Performance of Simple Seals in a Quasi Axisymmetric External Flow
,”
Int. J. Heat Fluid Flow
,
9
(2), pp.
106
112
.10.1016/0142-727X(88)90061-6
10.
Phadke
,
U. P.
, and
Owen
,
J. M.
,
1988
, “
Aerodynamic Aspects of the Sealing of Gas Turbine Rotor–Stator Systems, Part 3: The Effect of Nonaxisymmetric External Flow on Seal Performance
,”
Int. J. Heat Fluid Flow
,
9
(2), pp.
113
117
.10.1016/0142-727X(88)90062-8
11.
O'Mahoney
,
T. S. D.
,
Hills
,
N. J.
,
Chew
,
J. W.
, and
Scanlon
,
T.
,
2010
, “
Large-Eddy Simulation of Rim Seal Ingestion
,”
ASME
Paper No. GT2010-22962. 10.1115/GT2010-22962
12.
Dunn
,
D. M.
,
Zhou
,
D. W.
,
Saha
,
K.
,
Squires
,
K. D.
,
Roy
,
R. P.
,
Kim
,
Y. W.
, and
Moon
,
H. K.
,
2010
, “
Flow Field in a Single Stage Model Air Turbine Rotor–Stator Cavity With Pre-Swirled Purge Flow
,”
ASME
Paper No. GT2010-22869. 10.1115/GT2010-22869
13.
Wang
,
C. Z.
,
Johnson
,
B. V.
,
Mathiyalagan
,
S. P.
,
Glahn
,
J. A.
, and
Cloud
,
D. F.
,
2012
, “
Rim Seal Ingestion in a Turbine Stage From 360-Degree Time-Dependent Numerical Simulations
,”
ASME
Paper No. GT2012-68193. 10.1115/GT2012-68193
14.
Mirzamoghadam
,
A. V.
,
Giebert
,
D.
,
Molla-Hosseini
,
K.
, and
Bedrosyan
,
L.
,
2012
, “
The Influence of HPT Forward Disc Cavity Platform Axial Overlap Geometry on Mainstream Ingestion
,”
ASME
Paper No. GT2012-68429. 10.1115/GT2012-68429
15.
Craft
,
T.
,
Iacovides
,
H.
,
Launder
,
B.
, and
Zacharos
,
A.
,
2008
, “
Some Swirling-Flow Challenges for Turbulent CFD
,”
Flow, Turbul. Combust.
,
80
(
4
), pp.
419
434
.10.1007/s10494-008-9156-0
16.
Balasubramanian
,
J. H.
,
Pathak
,
P. S.
,
Thiagarajan
,
J. K.
,
Singh
,
P.
,
Roy
,
R. P.
, and
Mirzamoghadam
,
A. V.
,
2014
, “
Experimental Study of Ingestion in the Rotor–Stator Disk Cavity of a Subscale Axial Turbine Stage
,”
ASME
Paper No. GT2014-25487. 10.1115/GT2014-25487
17.
ANSYS, 2012, ANSYS FLUENT 14.5 Documentation
, Chapter 1.1, New Features in ANSYS FLUENT 14.5, Oct.,
2012
, ANSYS Inc., Canonsburg, PA.
18.
Czarny
,
O.
,
Iacovides
,
H.
, and
Launder
,
B. E.
,
2002
, “
Processing Vortex Structures in Turbulent Flow Within Rotor–Stator Disc Cavities
,”
Flow, Turbul. Combust.
,
69
(
1
), pp.
51
61
.10.1023/A:1022471329506
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