The secondary air system of a modern gas or steam turbine is configured to satisfy a number of requirements, such as to purge cavities and maintain a sufficient flow of cooling air to key engine components, for a minimum penalty on engine cycle efficiency and specific fuel consumption. Advanced sealing technologies, such as brush seals and leaf seals, are designed to maintain pressures in cavities adjacent to rotating shafts. They offer significant reductions in secondary air parasitic leakage flows over the legacy sealing technology, the labyrinth seal. The leaf seal comprises a series of stacked sheet elements which are inclined relative to the radial direction, offering increased axial rigidity, reduced radial stiffness, and good leakage performance. Investigations into leaf seal mechanical and flow performance have been conducted by previous researchers. However, limited understanding of the thermal behavior of contacting leaf seals under sustained shaft contact has led to the development of an analytical model in this study, which can be used to predict the power split between the leaf and rotor from predicted temperature rises during operation. This enables the effects of seal and rotor thermal growth and, therefore, implications on seal endurance and rotor mechanical integrity to be quantified. Consideration is given to the heat transfer coefficient in the leaf pack. A dimensional analysis of the leaf seal problem using the method of extended dimensions is presented, yielding the expected form of the relationship between seal frictional power generation, leakage mass flow rate, and rotor temperature rise. An analytical model is derived which is in agreement. Using the derived leaf temperature distribution formula, the theoretical leaf tip temperature rise and temperature distributions are computed over a range of mass flow rates and frictional heat values. Experimental data were collected in high-speed tests of a leaf seal prototype using the Engine Seal Test Facility at Oxford University. These data were used to populate the analytical model and collapsed well to confirm the expected linear relationship. In this form, the thermal characteristic can be used with predictions of mass flow rate and frictional power generated to estimate the leaf tip and rotor temperature rise in engine operation.

References

References
1.
Wright
,
C.
,
2001
, “
Resilient Strip Seal Arrangement
,”
U.S. Patent No. US6267381 B1
.
2.
Shinohara
,
T.
,
Akagi
,
K.
,
Yuri
,
M.
,
Toyoda
,
M.
,
Ozawa
,
Y.
,
Kawaguchi
,
A.
,
Sakakibara
,
S.
,
Yoshida
,
Z.
,
Kunitake
,
N.
,
Ohta
,
T.
,
Nakane
,
H.
,
Ito
,
E.
,
Kawata
,
Y.
, and
Takeshita
,
K.
,
2002
, “
Shaft Seal and Turbine Using the Same
,”
U.S. Patent No. US6343792 B1
.
3.
Nakane
,
H.
,
Maekawa
,
A.
,
Akita
,
E.
,
Akagi
,
K.
,
Nakano
,
T.
,
Nishimoto
,
S.
,
Hashimoto
,
S.
,
Shinohara
,
T.
, and
Uehara
,
H.
,
2002
, “
The Development of High Performance Leaf Seals
,”
ASME
Paper No. GT2002-30243.
4.
Nakane
,
H.
,
Maekawa
,
A.
,
Akita
,
E.
,
Akagi
,
K.
,
Nakano
,
T.
,
Nishimoto
,
S.
,
Hashimoto
,
S.
,
Shinohara
,
T.
, and
Uehara
,
H.
,
2004
, “
The Development of High-Performance Leaf Seals
,”
ASME J. Eng. Gas Turbines Power
,
126
(2), pp.
342
350
.
5.
Jahn
,
I. H. J.
,
Owen
,
A. K.
,
Franceschini
,
G.
, and
Gillespie
,
D. R. H.
,
2008
, “
Experimental Characterisation of the Stiffness and Leakage of a Prototype Leaf Seal for Gas Turbine Applications
,”
ASME
Paper No. GT2008-51206.
6.
Jahn
,
I. H. J.
,
Franceschini
,
G.
,
Owen
,
A. K.
, and
Gillespie
,
D. R. H.
,
2011
, “
Negative Stiffness in Gas Turbine Leaf Seals
,”
ASME
Paper No. GT2011-46483.
7.
Franceschini
,
G.
,
Jahn
,
I. H. J.
,
Owen
,
A. K.
,
Jones
,
T. V.
, and
Gillespie
,
D. R. H.
,
2012
, “
Improved Understanding of Negative Stiffness in Filament Seals
,”
ASME
Paper No. GT2012-68899.
8.
Owen
,
A. K.
,
Jones
,
T. V.
,
Guo
,
S. M.
, and
Hogg
,
S.
,
2003
, “
An Experimental and Theoretical Study of Brush Seal and Shaft Thermal Interaction
,”
ASME
Paper No. 2003-GT-38276.
9.
Pekris
,
M.
,
Franceschini
,
G.
, and
Gillespie
,
D. R. H.
,
2014
, “
An Investigation of Flow Mechanical and Thermal Performance of Conventional and Pressure-Balanced Brush Seals
,”
ASME J. Eng. Gas Turbines Power
,
136
(
6
), p.
062502
.
10.
Bo Qiu
,
J. L.
, and
Feng
,
Z.
,
2015
, “
Investigation of Conjugate Heat Transfer in Brush Seals Using Porous Media Approach Under Local Thermal Non-Equilibrium Conditions
,”
ASME
Paper No. GT2015-42550.
11.
Kays
,
W.
,
Crawford
,
M.
, and
Weigand
,
B.
,
2004
,
Convective Heat and Mass Transfer
,
4th ed.
,
McGraw-Hill
,
New York
.
12.
Isaacson
,
E.
, and
Isaacson
,
M.
,
1975
,
Dimensional Methods in Engineering and Physics
,
Wiley
, London.
13.
Abernethy
,
R. B.
,
Benedict
,
R. P.
, and
Dowdell
,
R. B.
,
1985
, “
ASME Measurement Uncertainty
,”
ASME J. Fluids Eng.
,
107
(
2
), pp.
161
164
.
14.
Moffat
,
R. J.
,
1988
, “
Describing the Uncertainties in Experimental Results
,”
Exp. Therm. Fluid Sci.
,
1
(1), pp.
3
17
.
15.
ASME
,
2005
, “
Test Uncertainty: Performance Test Codes
,” ASME, New York, Standard No. ASME PTC 19.1: 2005.
16.
Dogu
,
Y.
, and
Aksit
,
M. F.
,
2006
, “
Brush Seal Temperature Distribution Analysis
,”
ASME J. Eng. Gas Turbines Power
,
128
(
3
), pp.
599
609
.
17.
Wood
,
P. E.
, and
Jones
,
T. V.
,
1999
, “
A Test Facility for the Measurement of Torques at the Shaft to Seal Interface in Brush Seals
,”
ASME J. Eng. Gas Turbines Power
,
121
(
1
), pp.
160
166
.
18.
Pekris
,
M. J.
,
Franceschini
,
G.
,
Jahn
,
I. H.
, and
Gillespie
,
D. R. H.
,
2015
, “
Experimental Investigation of a Leaf Seal Prototype at Engine-Representative Speeds and Pressures
,”
ASME J. Eng. Gas Turbines Power
,
138
(
7
), p.
072502
.
19.
Pekris
,
M.
,
Franceschini
,
G.
, and
Gillespie
,
D. R. H.
,
2012
, “
An Investigation of Flow Mechanical and Thermal Performance of Conventional and Pressure-Balanced Brush Seals
,”
ASME
Paper No. GT2012-68901.
20.
BSI
,
1981
, “
British Standard Measurement of Fluid Flow in Closed Conduits
,” British Standards Institution, London, Section 1.1, Standard No. BS1042.
21.
Moffat
,
R. J.
,
1982
, “
Contributions to the Theory of Single-Sample Uncertainty Analysis
,”
ASME J. Fluids Eng.
,
104
(
2
), pp.
250
260
.
22.
Pekris
,
M. J.
,
Nasti
,
A.
,
Jahn
,
I. H.
, and
Franceschini
,
G.
,
2016
, “
High Speed Characterization of a Prototype Leaf Seal on an Advanced Seal Test Facility
,”
ASME J. Eng. Gas Turbines Power
,
138
(
8
), p.
082503
.
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