A large portion of the over-tip leakage flow is often transonic for a typical high pressure (HP) turbine blade. It has been observed that the tip heat transfer is noticeably lower in a high speed flow tip region than in a low speed region. The present study therefore investigates the feasibility of controlling blade heat transfer by tip shaping to locally accelerate the flow to a transonic regime. The results show that a significant heat load reduction can be achieved by the local flow acceleration. Such over-tip-shaping provides a great potential as an effective means to control heat load distribution (and hence thermal stress) over the blade tip surface. The feasibility of the concept and flow physics have been demonstrated in detail by CFD analyses, with and without the effect of moving casing. The experimental results obtained from a high speed linear cascade facility have also been presented. The novel tip-shaping concept proposed in this paper could provide a potential for promoting choking inside the tip gap as a new way to control the over-tip leakage mass flow.

References

References
1.
Heyes
,
F. J. G.
,
Hodson
,
H. P.
, and
Dailey
,
G. M.
,
1992
, “
The Effect of Blade Tip Geometry on the Tip Leakage Flow in Axial Turbine Cascades
,”
ASME J. Turbomach.
,
114
, pp.
643
651
.10.1115/1.2929188
2.
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
(
2
), pp.
213
220
.10.1115/1.2162183
3.
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
4.
Vass
,
P.
, and
Arts
,
T.
,
2011
, “
Advanced Aero-Thermal Investigation of High Pressure Turbine Tip Flows
,”
Heat Transfer Res.
,
42
(
2
), pp.
165
180
.
5.
Schabowski
,
Z.
, and
Hodson
,
H. P.
,
2007
, “
The Reduction of Over Tip Leakage Loss in Unshrouded Axial Turbines Using Winglets and Squealers
,”
ASME
Paper No. GT2007-27623. 10.1115/GT2007-27623
6.
Dey
,
D.
, and
Camci
,
C.
,
2001
, “
Aerodynamic Tip Desensitization of an Axial Turbine Rotor Using Tip Platform Extensions
,” ASME Paper No. 2001-GT-0484.
7.
Harvey
,
N. W.
, and
Ramsden
,
K.
,
2001
, “
A Computational Study of a Novel Turbine Rotor Partial Shroud
,”
ASME J. Turbomach.
,
123
, pp.
534
543
.10.1115/1.1370166
8.
Harvey
,
N. W.
,
Newman
,
D. A.
,
Haselbach
,
F.
, and
Willer
,
L.
,
2006
, “
An Investigation Into a Novel Turbine Rotor Winglet: Part I—Design and Model Rig Test Results
,”
ASME
Paper No. GT2006-90456. 10.1115/GT2006-90456
9.
Harvey
,
N. W.
,
Newman
,
D. A.
,
Haselbach
,
F.
, and
Willer
,
L.
,
2006
, “
An Investigation Into a Novel Turbine Rotor Winglet: Part 2—Numerical Simulation and Experimental Results
,”
ASME
Paper No. GT2006-90459. 10.1115/GT2006-90459
10.
Bunker
,
R. S.
,
2001
, “
A Review of Turbine Blade Tip Heat Transfer in Gas Turbine Systems
,”
Ann. N.Y. Acad. Sci.
,
934
, pp.
64
79
.10.1111/j.1749-6632.2001.tb05843.x
11.
Bunker
,
R. S.
, and
Bailey
,
J. C.
,
2000
, “
Effect of Squealer Cavity Depth and Oxidation on Turbine Blade Tip Heat Transfer
,” ASME Paper No. 2000-GT-0155.
12.
Newton
,
P. J.
,
Krishnababu
,
S. K.
,
Lock
,
G. D.
,
Hodson
,
H. P.
,
Dawes
,
W. N.
,
Hannis
,
J.
, and
Whitney
,
C.
,
2006
, “
Heat Transfer and Aerodynamics of Turbine Blade Tips in a Linear Cascade
,”
ASME J. Turbomach.
,
128
(
2
), pp.
300
309
.10.1115/1.2137745
13.
Krishnababu
,
S. K.
,
Newton
,
P. J.
,
Dawes
,
W. N.
,
Lock
,
G. D.
,
Hodson
,
H. P.
,
Hannis
,
J.
, and
Whitney
,
C.
,
2007
, “
Aero-Thermal Investigation of Tip Leakage Flow in Axial Turbines: Part I—Effect of Tip Geometry and Tip Clearance Gap
,”
ASME
Paper No. GT2007-27954. 10.1115/GT2007-27954
14.
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
, pp.
669
677
.10.1115/1.1571849
15.
Kwak
,
J. S.
,
Ahn
,
J.
,
Han
,
J. C.
,
Lee
,
C. P.
,
Bunker
,
R. S.
,
Boyle
,
R.
, and
Gaugler
,
R.
,
2003
, “
Heat Transfer Coefficients on the Squealer Tip and Near Tip Regions of a Gas Turbine Blade With Single or Double Squealer
,”
ASME
Paper No. GT2003-38907. 10.1115/GT2003-38907
16.
Azad
,
G. S.
,
Han
,
J.
, and
Boyle
,
R. J.
,
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
17.
Nasir
,
H.
,
Ekkad
,
S. V.
,
Kontrovitz
,
D. M.
,
Bunker
,
R. S.
, and
Prakash
,
C.
,
2004
, “
Effect of Tip Gap and Squealer Geometry on Detailed Heat Transfer Measurements Over a High Pressure Turbine Rotor Blade Tip
,”
ASME J. Turbomach.
,
126
(
2
), pp.
221
228
.10.1115/1.1731416
18.
Yang
,
H.
,
Chen
,
H. C.
, and
Han
,
J. C.
,
2006
, “
Turbine Rotor With Various Tip Configuration Flow and Heat Transfer Prediction
,”
AIAA J. Thermophys. Heat Transfer
,
20
(
1
), pp.
80
91
.10.2514/1.14949
19.
Yang
,
H.
,
Acharya
,
S.
,
Ekkad
,
S. V.
,
Prakash
,
C.
, and
Bunker
,
R. S.
,
2002
, “
Numerical Simulation of Flow and Heat Transfer Past a Turbine Blade With a Squealer Tip
,”
ASME
Paper No. GT-2002-30193. 10.1115/GT2002-30193
20.
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
21.
Mischo
,
B.
,
Behr
,
T.
, and
Abhari
,
R. S.
,
2006
, “
Flow Physics and Profiling of Recessed Blade Tips: Impact on Performance and Heat Load
,”
ASME
Paper No. GT2006-91074. 10.1115/GT2006-91074
22.
Saha
,
A. K.
,
Acharya
,
S.
,
Prakash
,
C.
, and
Bunker
,
R. S.
,
2003
, “
Blade Tip Leakage Flow and Heat Transfer With Pressure-Side Winglet
,”
ASME
Paper No. GT2003-38620. 10.1115/GT2003-38620
23.
Dunn
,
M. G.
, and
Haldeman
,
C. W.
,
2000
, “
Time-Averaged Heat Flux for a Recessed Tip, Lip, and Platform of a Transonic Turbine Blade
,”
ASME J. Turbomach.
,
122
, pp.
692
698
.10.1115/1.1311285
24.
O'Dowd
,
D.
,
Zhang
,
Q.
,
He
,
L.
,
Oldfield
,
M.
, and
Ligrani
,
P. M.
,
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
25.
Zhang
,
Q.
, and
He
,
L.
,
2011
, “
Over-Tip Choking and Its Implications on Turbine Blade Tip Aerodynamic Performance
,”
AIAA J. Propul. Power
,
27
(
5
), pp.
1008
1014
.10.2514/1.B34112
26.
Harvey
,
N. W.
,
2004
, “
Aerothermal Implications of Shroudless and Shrouded Blades
,”
Turbine Blade Tip Design and Tip Clearance (VKI Lecture Series 2004-02)
,
von Karman Institute, Rhode-St-Genese
,
Belgium
.
27.
Chen
,
G.
,
Dawes
,
W. N.
, and
Hodson
,
H. P.
,
1993
, “
A Numerical and Experimental Investigation of Turbine Tip Gap Flow
,”
Proceedings of the 29th Joint Propulsion Conference and Exhibit
,
1993
,
AIAA
Paper No. 93-2253. 10.2514/6.1993-2253
28.
Green
,
B. R.
,
Barter
,
J. W.
,
Haldeman
,
C. W.
, and
Dunn
,
M. G.
,
2005
, “
Averaged and Time—Dependent Aerodynamics of a High Pressure Turbine Blade Tip Cavity and Stationary Shroud: Comparison of Computational and Experimental Results
,”
ASME J. Turbomach.
,
127
, pp.
736
746
.10.1115/1.1934410
29.
Molter
,
S. M.
,
Dunn
,
M. G.
,
Haldeman
,
C. W.
,
Bergholz
,
R. F.
, and
Vitt
,
P.
,
2006
, “
Heat-Flux Measurements and Predictions for the Blade Tip Region of a High-Pressure Turbine
,”
ASME
Paper No. GT2006-90048. 10.1115/GT2006-90048
30.
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
31.
Shyam
,
V.
,
Ameri
,
A.
,
Luk
,
D. F.
, and
Chen
,
J. P.
,
2009
, “
3-D Unsteady Simulation of a Modern High Pressure Turbine Stage Using Phase Lag Periodicity: Analysis of Flow and Heat Transfer
,”
ASME
Paper No. GT2009-60322. 10.1115/GT2009-60322
32.
Shyam
,
V.
,
Ameri
,
A.
, and
Chen
,
J. P.
,
2012
, “
Analysis of Unsteady Tip and Endwall Heat Transfer in a Highly Loaded Transonic Turbine Stage
,”
ASME J. Turbomach.
,
134
, p.
041022
.10.1115/1.4003719
33.
Shyam
,
V.
, and
Ameri
,
A.
,
2011
, “
Comparison of Various Supersonic Turbine Tip Designs to Minimize Aerodynamic Loss and Tip Heating
,”
ASME
Paper No. GT2011-46390. 10.1115/GT2011-46390
34.
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
35.
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
36.
He
,
L.
,
Zhang
,
Q.
,
Wheeler
,
A. P. S.
, and
Atkins
,
N.
,
2009
, “
Over-Tip-Shaping for Heat Load Reduction
,”
Invention Submission Form No. 09231
,
Rolls-Royce, plc
,
London, UK
.
37.
He
,
L.
,
Zhang
,
Q.
,
Wheeler
,
A. P. S.
, and
Atkins
,
N.
,
2010
, “
Over-Tip-Shaping for Heat Load Reduction
,” UK Patent GB 1017797.0, UKIPO.
38.
O'Dowd
,
D.
,
Zhang
,
Q.
,
He
,
L.
,
Ligrani
,
P. M.
, and
Friedrichs
,
S.
,
2011
, “
Comparison of Heat Transfer Measurement Techniques on a Transonic Turbine Blade Tip
,”
ASME J. Turbomach.
,
133
, p.
021028
.10.1115/1.4001236
39.
Gillespie
,
D. R. H.
,
Wang
,
Z.
, and
Ireland
,
P. T.
,
1995
, “
Heating Element
,” British Patent Application PCT/GB96/2017.
40.
Oldfield
,
M. L. G.
,
2008
, “
Impulse Response Processing of Transient Heat Transfer Gauge Signals
,”
ASME J. Turbomach.
,
130
(
2
), p.
021023
.10.1115/1.2752188
41.
Kline
,
S. J.
, and
McClintock
,
F. A.
,
1953
, “
Describing Uncertainties in Single-Sample Experiments
,”
Mech. Eng.
,
75
(1)
, pp.
3
8
.
42.
Moffat
,
R. J.
,
1988
, “
Describing the Uncertainties in Experimental Results
,”
Exp. Therm. Fluid Sci.
,
1
, pp.
3
17
.10.1016/0894-1777(88)90043-X
43.
Coleman
,
H. W.
, and
Steele
,
W. G.
,
1989
,
Experimentation and Uncertainty Analysis for Engineers
,
John Wiley & Sons
,
New York
.
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