The over-tip-leakage (OTL) flow characteristics for a typical squealer tip of a high-pressure turbine blade, which consists of subsonic and transonic flow, have been numerically investigated in the present study, in comparison with the corresponding flat tip results. For the squealer tip employed, flow choking behavior still exists above the tip surface, even though the Mach number is lower and the transonic region is smaller than that for the flat tip. Detailed flow structure analysis shows that most of the fluid entering the squealer cavity is from the frontal leading edge region. The fluid migrates along the cavity and is ejected at various locations near the suction side rim. These fluids form a large subsonic flow zone under the supersonic flow passing over the tip gap which reduces the OTL flow flux. The squealer design works even in the presence of choked OTL flow. Comparisons between results from three different cavity depths with and without relative casing motion suggest that the over-tip-leakage flow flux has much dependence upon the cavity depth for the subsonic region, but is less sensitive to the depth for the transonic tip flow region. Such behavior has been confirmed with and without the existence of relative casing motion.

References

References
1.
Bunker
,
R. S.
,
2006
, “
Axial Turbine Blade Tips: Function, Design, and Durability
,”
AIAA J. Propul. Power
,
22
(
2
), pp.
271
285
.10.2514/1.11818
2.
Ameri
,
A. A.
,
Steinthorsson
,
E.
, and
Rigby
,
D. L.
,
1998
, “
Effect of Squealer Tip on Rotor Heat Transfer and Efficiency
,”
ASME J. Turbomach.
,
120
(
4
), pp.
753
759
.10.1115/1.2841786
3.
Acharya
,
S.
,
Yang
,
H.
,
Prakash
,
C.
, and
Bunker
,
R.
,
2003
, “
Numerical Study of Flow and Heat Transfer on a Blade Tip With Different Leakage Reduction Strategies
,”
ASME
Paper No. GT2003-38617.10.1115/GT2003-38617
4.
Azad
,
G. S.
,
Han
,
J. C.
,
Bunker
,
R. S.
, and
Lee
,
C. P.
,
2002
, “
Effect of Squealer Geometry Arrangement on a Gas Turbine Blade Tip Heat Transfer
,”
ASME J. Heat Transfer
,
124
(
3
), pp.
452
459
.10.1115/1.1471523
5.
Azad
,
G. S.
,
Han
,
J. C.
,
Teng
,
S.
, and
Robert
,
J. B.
,
2000
, “
Heat Transfer and Pressure Distributions on a Gas Turbine Blade Tip
,”
ASME J. Turbomach.
,
122
(
4
), pp.
717
724
.10.1115/1.1308567
6.
Azad
,
G. S.
,
Han
,
J. C.
, and
Robert
,
J. B.
,
2000
, “
Heat Transfer and Flow on the Squealer Tip of a Gas Turbine Blade
,”
ASME J. Turbomach.
,
122
(
4
), pp.
725
732
.10.1115/1.1311284
7.
Ahn
,
J.
,
Mhetras
,
S.
, and
Han
,
J. C.
,
2005
, “
Film-Cooling Effectiveness on a Gas Turbine Blade Tip Using Pressure-Sensitive Paint
,”
ASME J. Heat Transfer
,
127
, pp.
521
530
.10.1115/1.1909208
8.
Kwak
,
J. S.
, and
Han
,
J. C.
,
2003
, “
Heat Transfer Coefficients on the Squealer Tip and Near Squealer Tip Regions of a Gas Turbine Blade
,”
ASME J. Heat Transfer
,
125
(
4
), pp.
669
677
.10.1115/1.1571849
9.
Kwak
,
J. S.
, and
Han
,
J. C.
,
2003
, “
Heat Transfer Coefficients and Film Cooling Effectiveness on the Squealer Tip of a Gas Turbine Blade
,”
ASME J. Turbomach.
,
125
, pp.
648
657
.10.1115/1.1622712
10.
Lee
,
S. W.
, and
Kim
,
S. U.
,
2010
, “
Tip Gap Height Effects on the Aerodynamic Performance of a Cavity Squealer Tip in a Turbine Cascade in Comparison With Plane Tip Results: Part 1—Tip Gap Flow Structure
,”
Exp. Fluids
,
49
, pp.
1039
1051
.10.1007/s00348-010-0848-6
11.
Lee
,
S. W.
, and
Choi
,
M. Y.
,
2010
, “
Tip Gap Height Effects on the Aerodynamic Performance of a Cavity Squealer Tip in a Turbine Cascade in Comparison With Plane Tip Results: Part 2—Aerodynamic Losses
,”
Exp. Fluids
,
49
, pp.
713
723
.10.1007/s00348-010-0849-5
12.
Krishnababu
,
S. K.
,
Newton
,
P. J.
,
Dawes
,
W. N.
,
Lock
,
G. D.
, and
Hodson
,
H. P.
,
2009
, “
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part I: Effect of Tip Geometry and Tip Clearance Gap
,”
ASME J. Turbomach.
,
131
, p.
011006
.10.1115/1.2950068
13.
Krishnababu
,
S. K.
,
Dawes
,
W. N.
,
Hodson
,
H. P.
,
Lock
,
G. D.
, and
Hannis
,
J.
,
2009
, “
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part II: Effect of Relative Casing Motion
,”
ASME J. Turbomach.
,
131
, p.
011007
.10.1115/1.2952378
14.
Mischo
,
B.
,
Burdet
,
A.
, and
Abhari
,
R. S.
,
2011
, “
Influence of Stator-Rotor Interaction on the Aerothermal Performance of Recess Blade Tips
,”
ASME J. Turbomach.
,
133
, p.
011023
.10.1115/1.4001134
15.
Mischo
,
B.
,
Behr
,
T.
, and
Abhari
,
R. S.
,
2011
, “
Flow Physics and Profiling of Recessed Blade Tips: Impact on Performance and Heat Load
,”
ASME J. Turbomach.
,
130
, p.
021008
.10.1115/1.2775485
16.
Yang
,
H. T.
,
Acharya
,
S.
,
Ekkad
,
S. V.
,
Prakash
,
C.
, and
Bunker
,
R.
,
2002
, “
Numerical Simulation of Flow and Heat Transfer Past a Turbine Blade With a Squealer-Tip
,”
ASME
Paper No. GT2002-30193.10.1115/GT2002-30193
17.
Yang
,
H. T.
,
Chen
,
H.
, and
Han
,
J. C.
,
2006
, “
Turbine Rotor With Various Tip Configurations Flow and Heat Transfer Prediction
,”
J. Thermophysics Heat Transfer
,
20
(1), pp.
80
91
.10.2514/1.14949
18.
Zhang
,
Q.
,
O'Dowd
,
D.
,
He
,
L.
,
Wheeler
,
A. P. S.
,
Ligrani
,
P. M.
, and
Cheong
,
B. C. Y.
,
2011
, “
Over-Tip Shock Wave Structure and Its Impact on Turbine Blade Tip Heat Transfer
,”
ASME J. Turbomach.
,
133
, p.
041001
.10.1115/1.4002949
19.
Zhang
,
Q.
,
O'Dowd
,
D.
,
He
,
L.
,
Oldfield
,
M.
, and
Ligrani
,
P. M.
,
2011
, “
Transonic Turbine Blade Tip Aero-Thermal Performance With Different Tip Gaps: Part I—Tip Heat Transfer
,”
ASME J. Turbomach.
,
133
, p.
041027
.10.1115/1.4003063
20.
Zhang
,
Q.
, and
He
,
L.
,
2011
, “
Over-Tip Choking and Its Implications on Turbine Blade-Tip Aerodynamic Performance
,”
AIAA J. Propul. Power
,
27
, pp.
1008
1014
.10.2514/1.B34112
21.
O'Dowd
,
D.
,
Zhang
,
Q.
,
He
,
L.
,
Oldfield
,
M.
,
Ligrani
,
P. M.
,
Cheong
,
B. Y.
, and
Tibbott
,
I.
,
2011
, “
Aero-Thermal Performance of a Winglet Tip at Engine Representative Mach and Reynolds Numbers
,”
ASME J. Turbomach.
,
133
, p.
041026
.10.1115/1.4003055
22.
Wheeler
,
A. P. S.
,
Atkins
,
N. R.
, and
He
,
L.
,
2011
, “
Turbine Blade Tip Heat Transfer in Low Speed and High Speed Flows
,”
ASME J. Turbomach.
,
133
, p.
041025
.10.1115/1.4002424
23.
Wheeler
,
A. P. S.
,
Korakianitis
,
T.
, and
Banneheke
,
S.
,
2011
, “
Tip Leakage Losses in Subsonic and Transonic Blade-Rows
,”
ASME
Paper No. GT2011-45798.10.1115/GT2011-45798
24.
Hofer
,
T.
, and
Arts
,
T.
,
2009
, “
Aerodynamic Investigation of the Tip Leakage Flow for Blades With Different Tip Squealer Geometries at Transonic Conditions
,”
ASME
Paper No. GT2009-59909.10.1115/GT2009-59909
25.
Key
,
N. L.
, and
Arts
,
T.
,
2006
, “
Comparison of Turbine Tip Leakage Flow for Flat Tip and Squealer Tip Geometries at High-Speed Conditions
,”
ASME J. Turbomach.
,
128
, pp.
213
220
.10.1115/1.2162183
26.
Takayuki
,
M.
,
2006
, “
Effects of Reynolds Number and Freestream Turbulence on Turbine Tip Clearance Flow
,”
ASME J. Turbomach.
,
128
, pp.
166
177
.10.1115/1.2103091
27.
Schlichting
,
H.
,
1979
,
Boundary Layer Theory
,
McGraw-Hill
,
New York
, pp.
453
455
.
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