The objective of this work is to study the influence of a pressure side separation bubble on the profile losses and the development of the bubble in the blade passage. For the experimental investigations, the T106 profile is used, with an increased loading due to an enlarged pitch to chord ratio from 0.799 to 0.95 (T106C). The experiments were performed at the high-speed cascade wind tunnel of the Institute of Jet Propulsion at the University of the Federal Armed Forces Munich. The main feature of the wind tunnel is to vary Reynolds and Mach number independently to achieve realistic turbomachinery conditions. The focus of this work is to determine the influence of a pressure side separation on the profile losses and hence the robustness to suction side incidence flow. The cascade is tested at four incidence angles from 0 deg to −22.7 deg to create separation bubbles of different sizes. The influence of the Reynolds number is investigated for a wide range at constant exit Mach number. Therefore, a typical exit Mach number for low pressure turbines in the range of 0.5–0.8 is chosen in order to consider compressible effects. Furthermore, two inlet turbulence levels of about 3% and 7.5% have been considered. The characteristics of the separation bubble are identified by using the profile pressure distributions, whereas wake traverses with a five hole probe are used to determine the influence of the pressure side separation on the profile losses. Further, time-resolved pressure measurements near the trailing edge as well as single hot wire measurements in the blade passage are conducted to investigate the unsteady behavior of the pressure side separation process itself and also its influence on the midspan passage flow.

References

References
1.
Banieghbal
,
M.
,
Curtis
,
E.
,
Denton
,
J.
,
Hodson
,
H.
,
Huntsman
,
I.
,
Schulte
,
V.
,
Harvey
,
N.
, and
Steele
,
A.
,
1995
, “
Wake Passing in LP Turbine Blades
,” Loss Mechanisms and Unsteady Flows in Turbomachines, Derby, UK, Paper No. AGARD-CP-571, pp.
23-1
23-12
.
2.
Curtis
,
E. M.
,
Hodson
,
H. P.
,
Banieghbal
,
M. R.
,
Denton
,
J. D.
,
Howell
,
R. J.
, and
Harvey
,
N. W.
,
1997
, “
Development of Blade Profiles for Low-Pressure Turbine Applications
,”
ASME J. Turbomach.
,
119
(
3
), pp.
531
538
.
3.
Denton
,
J. D.
,
1993
, “
The 1993 IGTI Scholar Lecture: Loss Mechanisms in Turbomachines
,”
ASME J. Turbomach.
,
115
(
4
), pp.
621
656
.
4.
Lichtfuß
,
H. J.
,
2004
, “
Customized Profiles the Beginning of an Era: A Short History of Blade Design
,”
ASME
Paper No. GT2004-53742.
5.
Brear
,
M. J.
,
Hodson
,
H. P.
, and
Harvey
,
N. W.
,
2002
, “
Pressure Surface Separations in Low-Pressure Turbines—Part 1: Midspan Behavior
,”
ASME J. Turbomach.
,
124
(
3
), pp.
393
401
.
6.
Hodson
,
H.
,
1986
, “
The Off-Design Performance of a Low-Pressure Turbine Cascade
,”
ASME J. Turbomach.
,
109
(
2
), pp.
201
209
.
7.
González
,
P.
,
Ulizar
,
I.
,
Vázquez
,
R.
, and
Hodson
,
H. P.
,
2002
, “
Pressure and Suction Surfaces Redesign for High-Lift Low-Pressure Turbines
,”
ASME J. Turbomach.
,
124
(
2
), pp.
161
166
.
8.
Yamamoto
,
A.
, and
Nouse
,
H.
,
1988
, “
Effects of Incidence on Three-Dimensional Flows in a Linear Turbine Cascade
,”
ASME J. Turbomach.
,
110
(
4
), pp.
486
496
.
9.
Brear
,
M. J.
,
Hodson
,
H. P.
,
Gonzalez
,
P.
, and
Harvey
,
N. W.
,
2002
, “
Pressure Surface Separations in Low-Pressure Turbines—Part 2: Interactions With the Secondary Flow
,”
ASME J. Turbomach.
,
124
(
3
), pp.
402
409
.
10.
Gomes
,
R. A.
, and
Niehuis
,
R.
,
2012
, “
Film Cooling on Highly Loaded Blades With Main Flow Separation—Part I: Heat Transfer
,”
ASME J. Turbomach.
,
135
(
1
), p.
011043
.
11.
Ladisch
,
H.
,
Schulz
,
A.
, and
Bauer
,
H.-J.
,
2009
, “
Heat Transfer Measurements on a Turbine Airfoil With Pressure Side Separation
,”
ASME
Paper No. GT2009-59904.
12.
Walraevens
,
R. E.
, and
Cumpsty
,
N. A.
,
1995
, “
Leading Edge Separation Bubbles on Turbomachine Blades
,”
ASME J. Turbomach.
,
117
(
1
), pp.
115
125
.
13.
Hazarika
,
B. K.
, and
Hirsch
,
C.
,
1997
, “
Transition Over C4 Leading Edge and Measurement of Intermittency Factor Using PDF of Hot-Wire Signal
,”
ASME J. Turbomach.
,
119
(
3
), pp.
412
425
.
14.
Samson
,
A.
, and
Sarkar
,
S.
,
2016
, “
Effects of Free-Stream Turbulence on Transition of a Separated Boundary Layer Over the Leading-Edge of a Constant Thickness Airfoil
,”
ASME J. Fluids Eng.
,
138
(
2
), p.
021202
.
15.
Sturm
,
W.
, and
Fottner
,
L.
,
1985
, “
The High-Speed Cascade Wind Tunnel of the German Armed Forces University Munich
,”
8th Symposium on Measuring Techniques for Transonic and Supersonic Flows in Cascades and Turbomachines
, Genova, Italy.
16.
Lichtfuß
,
H. J.
,
1979
, “
Awendung neuer Entwurfskonzepte auf Profile für Axiale Turbomaschinen, Teil II: Optimale Geschwindigkeitsverteilungen für die Auslegung von Verdichter- und Turbinengittern
,” Technischer Bericht 78/054 B, MTU-München. ZTL-Abschlussbericht 1978.
17.
Hoheisel
,
H.
,
Kiock
,
R.
,
Lichtfuss
,
H. J.
, and
Fottner
,
L.
,
1987
, “
Influence of Free-Stream Turbulence and Blade Pressure Gradient on Boundary Layer and Loss Behavior of Turbine Cascades
,”
ASME J. Turbomach.
,
109
(
2
), pp.
210
219
.
18.
Stieger
,
R. D.
,
Hollis
,
D.
, and
Hodson
,
H. P.
,
2004
, “
Unsteady Surface Pressures Due to Wake-Induced Transition in a Laminar Separation Bubble on a Low-Pressure Cascade
,”
ASME J. Turbomach.
,
126
(
4
), pp.
544
550
.
19.
Montis
,
M.
,
Fiala
,
A.
, and
Niehuis
,
R.
,
2010
, “
Effect of Surface Roughness on Loss Behaviour, Aerodynamic Loading and Boundary Layer Development of a Low-Pressure Gas Turbine Airfoil
,”
ASME
Paper No. GT2010-23317.
20.
Gier
,
J.
,
Franke
,
M.
,
Hübner
,
N.
, and
Schröder
,
T.
,
2010
, “
Designing Low Pressure Turbines for Optimized Airfoil Lift
,”
ASME J. Turbomach.
,
132
(
3
), p.
031008
.
21.
Marciniak
,
V.
,
Kügler
,
E.
, and
Franke
,
M.
,
2010
, “
Predicting Transition on Low-Pressure Turbine Profiles
,”
V European Conference on Computational Fluid Dynamics
,
ECCOMAS CFD
2010, Lisbon, Portugal, June 15–17.https://www.researchgate.net/profile/Vincent_Marciniak/publication/225006418_Predicting_Transition_on_Low-Pressure_Turbine_Profiles/links/5447a5460cf2d62c30508d36.pdf
22.
Michàlek
,
J.
,
Monaldi
,
M.
, and
Arts
,
T.
,
2012
, “
Aerodynamic Performance of a Very High Lift Low Pressure Turbine Airfoil (T106C) at Low Reynolds and High Mach Number With Effect of Free Stream Turbulence Intensity
,”
ASME J. Turbomach.
,
134
(
6
), p.
061009
.
23.
Ciorciari
,
R.
,
Kirik
,
I.
, and
Niehuis
,
R.
,
2014
, “
Effects of Unsteady Wakes on the Secondary Flows in the Linear T106 Turbine Cascade
,”
ASME J. Turbomach.
,
136
(
9
), p.
091010
.
24.
Hoheisel
,
H.
,
1990
, “
Test Cases for Computation of Internal Flows in Aero Engine Components: Test Case E/CA6, Subsonic Turbine Cascade T106
,” Technical Report No. AGARD-AR-275.
25.
Traupel
,
W.
,
2001
,
Thermische Turbomaschinen
,
Springer-Verlag
,
Berlin
, p.
271
.
26.
Amecke
,
J.
,
1967
, “
Auswertung von Nachlaufmessungen an Ebenen Schaufelgittern
,” AVA Göttingen, Göttingen, Germany, Technical Report No. 67 A 49.
27.
Ruck
,
G.
,
1989
, “
Ein Verfahren zur Instationären Geschwindigkeits- und Turbulenzmessung mit einer Pneumatischen Keilsonde
,” Ph.D. thesis, Universität Stuttgart, Stuttgart, Germany.
28.
Hänsel
,
H.
,
1967
,
Grundzüge der Fehlerrechnung
,
Deutscher Verlag der Wissenschaften
,
Berlin
.
29.
Drela
,
M.
, and
Youngren
,
H.
,
1998
,
A User's Guide to MISES 2.53
,
MIT Computational Aerospace Sciences Laboratory
, Cambridge, MA.
30.
Watmuff
,
J. H.
,
1999
, “
Evolution of a Wave Packet Into Vortex Loops in a Laminar Separation Bubble
,”
J. Fluid Mech.
,
397
, pp.
119
169
.
31.
Lou
,
W.
, and
Hourmouziadis
,
J.
,
2000
, “
Separation Bubbles Under Steady and Periodic-Unsteady Main Flow Conditions
,”
ASME J. Turbomach.
,
122
(
4
), pp.
634
643
.
32.
Satta
,
F.
,
Simoni
,
D.
,
Ubaldi
,
M.
,
Zunino
,
P.
, and
Bertini
,
F.
,
2011
, “
Separated-Flow Transition Process on a Lowpressure Turbine Blade Under Steady and Unsteady Inflows
,” ETC 9, Paper No. 260.
33.
Simoni
,
D.
,
Ubaldi
,
M.
,
Zunino
,
P.
,
Lengani
,
D.
, and
Bertini
,
F.
,
2012
, “
An Experimental Investigation of the Separated-Flow Transition Under High-Lift Turbine Blade Pressure Gradients
,”
Flow, Turbul. Combust.
,
88
, pp.
45
62
.
34.
Bradshaw
,
P.
,
1971
,
An Introduction to Turbulence and Its Measurements
,
Pergamon Press
,
Oxford, UK
.
35.
Chandrasekhar
,
S.
,
1981
,
Hydrodynamic and Hydromagnetic Stability
,
Dover Publications
,
New York
.
36.
Schmid
,
P. J.
, and
Henningson
,
D. S.
,
2001
,
Stability and Transition in Shear Flows
,
Springer
,
New York
.
37.
Yang
,
Z.
, and
Voke
,
P. R.
,
2001
, “
Large-Eddy Simulation of Boundary-Layer Separation and Transition at a Change of Surface Curvature
,”
J. Fluid Mech.
,
439
, pp.
305
333
.
38.
Simoni
,
D.
,
Ubaldi
,
M.
, and
Zunino
,
P.
,
2015
, “
A Simplified Model Predicting the Kelvin–Helmholtz Instability Frequency for Laminar Separated Flows
,”
ASME J. Turbomach.
,
138
(
4
), p.
044501
.
39.
McAuliffe
,
B. R.
, and
Yaras
,
M. I.
,
2010
, “
Transition Mechanisms in Separation Bubbles Under Low- and Elevated-Freestream Turbulence
,”
ASME J. Turbomach.
,
132
(
1
), p.
011004
.
40.
Mayle
,
R. E.
,
1991
, “
The Role of Laminar-Turbulent Transition in Gas Turbine Engines
,”
ASME J. Turbomach.
,
113
(
4
), pp.
509
536
.
41.
Pope
,
S. B.
,
2001
,
Turbulent Flows
,
Cambridge University Press
, Cambridge, UK.
You do not currently have access to this content.