A comparative experimental and numerical analysis is carried out to assess the aerodynamic performance of a novel partial shroud in a straight turbine cascade. This partial shroud is designed as a combination of winglet and shroud. A plain tip is employed as a baseline case. A pure winglet tip is also studied for comparison. Both experiments and predictions demonstrate that this novel partial shroud configuration has aerodynamic advantages over the pure winglet arrangement. Predicted results show that, relative to the baseline blade with a plain tip, using the partial shroud can lead to a reduction of 20.89% in the mass-averaged total pressure coefficient on the upper half-span of a plane downstream of the cascade trailing edge and 16.53% in the tip leakage mass flow rate, whereas the pure winglet only decreases these two performance parameters by 11.36% and 1.32%, respectively. The flow physics is explored in detail to explain these results via topological analyses. The use of this new partial shroud significantly affects the topological structures and total pressure loss coefficients on various axial cross sections, particularly at the rear part of the blade passage. The partial shroud not only weakens the tip leakage vortex (TLV) but also reduces the strength of passage vortex near the casing (PVC) endwall. Furthermore, three partial shrouds with width-to-pitch ratios of 3%, 5%, and 7% are considered. With an increase in the width of the winglet part, improvements in aerodynamics and the tip leakage mass flow rate are limited.

References

References
1.
Patel
,
K. V.
,
1980
, “
Research on a High Work Axial Gas Generator Turbine
,”
SAE
Technical Paper No. 800618.
2.
Harvey
,
N. W.
, and
Ramsden
,
K.
,
2001
, “
A Computational Study of a Novel Turbine Rotor Partial Shroud
,”
ASME J. Turbomach.
,
123
(
3
), pp.
534
543
.
3.
Shavalikul
,
A.
, and
Camci
,
C.
,
2008
, “
A Comparative Analysis of Pressure Side Extensions for Tip Leakage Control in Axial Turbines
,”
ASME
Paper No. GT2008-50782.
4.
Dey
,
D.
, and
Camci
,
C.
,
2001
, “
Aerodynamic Tip Desensitization of an Axial Turbine Rotor Using Tip Platform Extensions
,”
ASME
Paper No. 2001-GT-0484.
5.
Schabowski
,
Z.
, and
Hodson
,
H.
,
2013
, “
The Reduction of Over Tip Leakage Loss in Unshrouded Axial Turbines Using Winglets and Squealers
,”
ASME J. Turbomach.
,
136
(
4
), p.
041001
.
6.
Schabowski
,
Z.
,
Hodson
,
H.
,
Giacche
,
D.
,
Power
,
B.
, and
Stokes
,
M. R.
,
2014
, “
Aeromechanical Optimization of a Winglet-Squealer Tip for an Axial Turbine
,”
ASME J. Turbomach.
,
136
(
7
), p.
071004
.
7.
Zhou
,
C.
,
Hodson
,
H.
,
Tibbott
,
I.
, and
Stokes
,
M.
,
2013
, “
Effects of Winglet Geometry on the Aerodynamic Performance of Tip Leakage Flow in a Turbine Cascade
,”
ASME J. Turbomach.
,
135
(
5
), p.
051009
.
8.
Zhou
,
C.
,
Hodson
,
H.
,
Tibbott
,
I.
, and
Stokes
,
M.
,
2013
, “
The Aerothermal Performance of a Cooled Winglet Tip in a High Pressure Turbine Cascade
,”
ASME J. Turbomach.
,
135
(
3
), p.
031005
.
9.
Krishnababu
,
S. K.
,
Newton
,
P. J.
,
Dawes
,
W. N.
,
Lock
,
G. D.
,
Hodson
,
H. P.
,
Hannis
,
J.
, and
Whitney
,
C.
,
2008
, “
Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part I: Effect of Tip Geometry and Tip Clearance Gap
,”
ASME J. Turbomach.
,
131
(
1
), p.
011006
.
10.
Han
,
S. B.
,
Zhong
,
J. J.
,
Lu
,
H. W.
,
Kan
,
X. X.
, and
Yang
,
L.
,
2014
, “
Effect of Winglet Geometry Arrangement and Incidence on Tip Clearance Control in a Compressor Cascade
,”
J. Therm. Sci.
,
23
(
4
), pp.
381
390
.
11.
Aktuürk
,
A.
, and
Camci
,
C.
,
2010
, “
Axial Flow Fan Tip Leakage Flow Control Using Tip Platform Extensions
,”
ASME J. Fluids Eng.
,
132
(
5
), p.
051109
.
12.
Denton
,
J. D.
,
1993
, “
The 1993 IGTI Scholar Lecture: Loss Mechanisms in Turbomachines
,”
ASME J. Turbomach.
,
115
(
4
), pp.
621
656
.
13.
Bunker
,
R. S.
,
2006
, “
Axial Turbine Blade Tips: Function, Design, and Durability
,”
AIAA J. Propul. Power
,
22
(
2
), pp.
271
285
.
14.
Gao
,
J.
, and
Zheng
,
Q.
,
2014
, “
Comparative Investigation of Unsteady Flow Interactions in Endwall Regions of Shrouded and Unshrouded Turbines
,”
Comput. Fluids
,
105
, pp.
204
217
.
15.
Nirmalan
,
N. V.
, and
Bailey
,
J. C.
,
2005
, “
Experimental Investigation of Aerodynamic Losses of Different Shapes of a Shrouded Blade Tip Section
,”
ASME
Paper No. GT2005-68903.
16.
Porreca
,
L.
,
Behr
,
T.
,
Schlienger
,
J.
,
Kalfas
,
A. I.
,
Abhari
,
R. S.
,
Ehrhard
,
J.
, and
Janke
,
E.
,
2004
, “
Fluid Dynamics and Performance of Partially and Fully Shrouded Axial Turbines
,”
ASME J. Turbomach.
,
127
(
4
), pp.
668
678
.
17.
Porreca
,
L.
,
Kalfas
,
A. I.
, and
Abhari
,
R. S.
,
2008
, “
Optimized Shroud Design for Axial Turbine Aerodynamic Performance
,”
ASME J. Turbomach.
,
130
(
3
), p.
031016
.
18.
Behr
,
T.
,
2007
, “
Control of Rotor Tip Leakage and Secondary Flow by Casing Air Injection in Unshrouded Axial Turbine
,” Ph.D. thesis, Swiss Federal Institute of Technology, Zurich, Switzerland.
19.
Treaster
,
A. L.
, and
Yocum
,
A. M.
,
1979
, “
The Calibration and Application of Five-Hole Probes
,”
ISA Trans.
,
18
(
3
), pp.
23
34
.
20.
Celik
, I
. B.
,
Ghia
,
U.
,
Roache
,
P. J.
,
Freitas
,
C. J.
,
Coleman
,
H.
, and
Raad
,
P. E.
,
2008
, “
Procedure for Estimation and Reporting of Uncertainty Due to Discretization in CFD Applications
,”
ASME. J. Fluids Eng.
,
130
(
7
), p.
078001
.
21.
Kumar
,
K. N.
, and
Govardhan
,
M.
,
2014
, “
On Topology of Flow in a Turbine Cascade
,”
ASME J. Fluids Eng.
,
136
(
8
), p.
081201
.
22.
Zhou
,
J.
,
Adrian
,
R. J.
,
Balachandar
,
S.
, and
Kendall
,
T. M.
,
1999
, “
Mechanisms for Generating Coherent Packets of Hairpin Vortices in Channel Flow
,”
J. Fluid Mech.
,
387
, pp.
353
396
.
23.
Lee
,
S. W.
,
Kim
,
S. U.
, and
Kim
,
K. H.
,
2012
, “
Aerodynamic Performance of Winglets Covering the Tip Gap Inlet in a Turbine Cascade
,”
Int. J. Heat Fluid Flow
,
34
, pp.
36
46
.
You do not currently have access to this content.