Within a European research project, the tip endwall region of low pressure turbine guide vanes with leakage ejection was investigated at DLR in Göttingen. For this purpose a new cascade wind tunnel with three large profiles in the test section and a contoured endwall was designed and built, representing 50% height of a real low pressure turbine stator and simulating the casing flow field of shrouded vanes. The effect of tip leakage flow was simulated by blowing air through a small leakage gap in the endwall just upstream of the vane leading edges. Engine relevant turbulence intensities were adjusted by an active turbulence generator mounted in the test section inlet plane. The experiments were performed with tangential and perpendicular leakage ejection and varying leakage mass flow rates up to 2%. Aerodynamic and thermodynamic measurement techniques were employed. Pressure distribution measurements provided information about the endwall and vane surface pressure field and its variation with leakage flow. Additionally streamline patterns (local shear stress directions) on the walls were detected by oil flow visualization. Downstream traverses with five-hole pyramid type probes allow a survey of the secondary flow behavior in the cascade exit plane. The flow field in the near endwall area downstream of the leakage gap and around the vane leading edges was investigated using a 2D particle image velocimetry system. In order to determine endwall heat transfer distributions, the wall temperatures were measured by an infrared camera system, while heat fluxes at the surfaces were generated with electric operating heating foils. It turned out from the experiments that distinct changes in the secondary flow behavior and endwall heat transfer occur mainly when the leakage mass flow rate is increased from 1% to 2%. Leakage ejection perpendicular to the main flow direction amplifies the secondary flow, in particular the horseshoe vortex, whereas tangential leakage ejection causes a significant reduction of this vortex system. For high leakage mass flow rates the boundary layer flow at the endwall is strongly affected and seems to be highly turbulent, resulting in entirely different heat transfer distributions.

1.
Langston
,
S.
, 1980, “
Crossflow in a Turbine Cascade Passage
,”
J. Eng. Power
0022-0825,
102
, pp.
866
874
.
2.
Sieverding
,
C. H.
, 1985, “
Recent Progress in the Understanding of Basic Aspects of Secondary Flows in Turbine Blade Passages
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
107
, pp.
248
257
.
3.
Hodson
,
H. P.
, and
Dominy
,
R. G.
, 1986, “
Three-Dimensional Flow in a Low-Pressure Turbine Cascade at Its Design Condition
,” ASME Paper No. 86-GT-106.
4.
Piggush
,
J. D.
, and
Simon
,
T. W.
, 2005, “
Flow Measurements in a First Stage Nozzle Cascade Having Endwall Contouring, Leakage and Assembly Features
,” ASME Paper No. GT2005-68340.
5.
De la Rosa Blanco
,
E.
, and
Hodson
,
H. P.
, 2005, “
Effect of Upstream Platform Geometry on the Endwall Flows of a Turbine Cascade
,” ASME Paper No. GT2005-68938.
6.
Goldstein
,
R. J.
, and
Spores
,
R. A.
, 1988, “
Turbulent Transport on the Endwall in the Region between Adjacent Turbine Blades
,”
ASME J. Heat Transfer
0022-1481,
110
, pp.
863
869
.
7.
Graziani
,
R. A.
,
Blair
,
M. F.
,
Taylor
,
J. R.
, and
Mayle
,
R. E.
, 1980, “
An Experimental Study of Endwall and Airfoil Surface Heat Transfer in a Large Scale Turbine Blade Cascade
,”
ASME J. Eng. Power
0022-0825,
102
, pp.
257
267
.
8.
Takeishi
,
K.
,
Matsuura
,
M.
,
Aoki
,
S.
, and
Sato
,
T.
, 1990, “
An Experimental Study of Heat Transfer and Film Cooling on Low Aspect Ratio Turbine Nozzles
,”
ASME J. Turbomach.
0889-504X,
112
, pp.
489
496
.
9.
Kost
,
F.
, and
Nicklas
,
M.
, 2001, “
Film-Cooled Turbine Endwall in a Transonic Flow Field: Part I—Aerodynamic Measurements
,” ASME Paper No. 2001-GT-0145.
10.
Nicklas
,
M.
, 2001, “
Film-Cooled Turbine Endwall in a Transonic Flow Field: Part II—Heat Transfer and Film Cooling Effectiviness
,” ASME Paper No. 2001-GT-0146.
11.
Lee
,
S. W.
,
Park
,
B. K.
, and
Lee
,
J. S.
, 2002, “
Effects of High Free-Stream Turbulence on the Near-Wall Flow and Heat/Mass Transfer on the Endwall of a Linear Turbine Rotor Cascade
,” ASME Paper No. GT2002-30187.
12.
Pasinato
,
H. D.
,
Liu
,
Z.
,
Roy
,
R. P.
,
Howe
,
W. J.
, and
Squires
,
K. D.
, 2002, “
Prediction and Measurement of the Flow and Heat Transfer Along the Endwall and Within an Inlet Vane Passage
,” ASME Paper No. GT2002-30189.
13.
Haselbach
,
F.
, and
Schiffer
,
H. P.
, 2004, “
Aerothermal Investigations on Turbine Endwalls and Blades (AITEB)
,” ASME Paper No. GT2004-53078.
14.
Rehder
,
H.-J.
, and
Dannhauer
,
A.
, 2004, “
DLR Rig Instrumentation—European Research Project AITEB
,” DLR Internal Report IB 225-2004 A 08.
15.
Raffel
,
M.
,
Willert
,
C.
, and
Kompenhans
,
J.
, 1998,
Particle Image Velocimetry—A Practical Guide
,
Springer-Verlag
,
Berlin
.
16.
Giess
,
P.-A.
,
Rehder
,
H.-J.
, and
Kost
,
F.
, 2000, “
A New Test Facility for Probe Calibration—Offering Independent Variation of Mach and Reynolds Number
,”
15th Symposium on Measuring Techniques in Transonic and Supersonic Flow in Cascades and Turbomachines
,
Firenze, Italy
, September.
17.
Eckert
,
E. R. G.
, and
Goldstein
,
R. J.
,
Measurements in Heat Transfer
,
2nd ed.
,
McGraw-Hill
,
New York
.
18.
Eckert
,
E. R. G.
, 1984, “
Analysis of Film Cooling and Full-Coverage Film Cooling of Gas Turbine Blades
,”
ASME J. Eng. Gas Turbines Power
0742-4795,
106
, pp.
206
213
.
19.
Teekaram
,
A. J. H.
,
Forth
,
C. J. P.
, and
Jones
,
T. V.
, 1984, “
Cooling in the Presence of Mainstream Pressure Gradients
,”
ASME J. Turbomach.
0889-504X,
113
, pp.
484
492
.
20.
ISO
, 1993,
Guide to the Expression of Uncertainty in Measurement
, Geneva, Switzerland, ISBN 92-67-10188-9.
21.
Amecke
,
J.
, and
Šafařík
,
P.
, 1995, “
Data Reduction of Wake Flow Measurements with Injection of an Other Gas
,” Forschungsbericht DLR-FB 95-32, Cologne.
You do not currently have access to this content.