The understanding of the tip clearance flow in axial compressors is a key issue for developing new compressors with enhanced efficiency and reduced noise for instance. However, necessary flow measurements in the blade tip region and within the tip clearance are challenging due to the small gap width. The application of a novel optical measurement technique named Doppler global velocimetry with laser frequency modulation is presented, which provides velocity field measurements of all three velocity components nonintrusively in the tip clearance flow of a linear cascade at near stall conditions. These array measurements have a high temporal resolution enabling turbulence analysis such as the evaluation of velocity standard deviations and turbulence spectra up to several kilohertz. Conventional pneumatic and hot-wire measurements in planes at the inlet and the outlet as well as on the blade surface were taken to complete the flow pattern and validate the data of the Doppler global velocimetry. Wake measurements identified a strong flow separation in the rear suction side dominating the transient character of the cascade flow. Towards the endwall this high loss region is reduced by the clearance flow and the resulting vortex, which is obviously not affected by the profile separation and the pulsating blockage frequency. Inside the blade passage and the tip clearance the Doppler global velocimetry measurements allowed a spatial assignment of the origin of the tip leakage flow and the downstream developing vortex. In addition, the tip clearance vortex could be resolved and identified successfully as the most dominant turbulence generating effect in the near endwall region at this high loading operating point of the blading.

References

References
1.
Wisler
,
D. C.
, 1985, “
Loss Reduction in Axial Flow Compressors Trough Low-Speed Model Testing
,”
ASME J. Turbomach.
,
107
, pp.
354
363
.
2.
Hoying
,
D. A.
,
Tan
,
C. S.
,
Vo
,
H. D.
, and
Greitzer
,
E. M.
, 1998, “
Role of Blade Passage Flow Structures in Axial Compressor Rotating Stall Inception
,”
ASME J. Turbomach.
,
121
, pp.
735
742
.
3.
Mailach
,
R.
,
Lehmann
,
I.
, and
Vogeler
,
K.
, 2001, “
Rotating Instabilities in an Axial Compressor Originating from the Fluctuating Blade Tip Vortex
,”
ASME J. Turbomach.
,
123
, pp.
453
463
.
4.
Vo
,
D. H.
,
Tan
,
C. S.
, and
Greitzer
,
E. M.
, 2008, “
Criteria for Spike Initiated Rotating Stall
,”
ASME J. Turbomach.
,
130
, p.
011023
.
5.
Chen
,
G. T.
,
Greitzer
,
E. M.
,
Tan
,
C. S.
, and
Marble
,
F. E.
, 1991, “Similarity Analysis of Compressor Tip Clearance Flow Structure,”
ASME J. Turbomach.
,
113
, pp.
260
271
.
6.
Storer
,
J. A.
, and
Cumpsty
,
N. A.
, 1991, “
Tip Leakage Flow in Axial Compressors
,”
ASME J. Turbomach.
,
113
, pp.
252
259
.
7.
Lakshminarayana
,
B.
,
Zaccaria
,
M.
, and
Marathe
,
B.
, 1995, “
The Structure of Tip Clearance Flow in Axial Flow Compressors
,”
ASME J. Turbomach.
,
117
, pp.
336
347
.
8.
Tan
,
C. S.
, 2006, “
Three-Dimensional and Tip Clearance Flows in Compressors
,”
Advances in Axial Compressor Aerodynamics (VKI Lecture Series 2006-06) von Karman Institute for Fluid Dynamics,
Rhode-Saint-Genese
,
Belgium
, May
15
18
.
9.
Sell
,
M.
,
Treiber
,
M.
,
Casciaro
,
C.
, and
Gyarmathy
,
G.
, 1999, “
Tip-Clearance-Affected Flow Fields in a Turbine Blade Row
,”
Proc. Inst. Mech. Eng. Part A
,
213
, pp.
309
318
.
10.
Murthy
,
K. N. S.
, and
Lakshminarayana
,
B.
, 1986, “
Laser Doppler Velocimeter Measurements in the Tip Region of a Compressor Rotor
,”
AIAA J.
,
24
, pp.
807
814
.
11.
Stauter
,
R. C.
,
Dring
,
R. P.
, and
Carta
,
F. O.
, 1991, “
Temporally and Spatially Resolved Flow in a Two-Stage Axial Compressor: Part 1—Experiment
,”
ASME J. Turbomach.
,
113
, pp.
212
226
.
12.
Hathaway
,
M. D.
,
Suder
,
K. L.
,
Okiishi
,
T. H.
,
Strazisar
,
A. J.
, and
Adamczyk
,
J. J.
, 1987, “
Measurement of the Unsteady Flow Field Within the Stator Row of a Transonic Axial-Flow Fan: Part II—Results and Discussion
,” ASME Paper No. 87-GT-227.
13.
Lehmann
,
I.
,
Wolf
,
E.
, and
Vogeler
,
K.
, 2001, “
Stator Wake Propagation Inside Rotating Blade Passages
,” ImechE C557/006/99,
Proceedings of the 4th European Conference on Turbomachinery
,
Florence
,
Italy
.
14.
Mailach
,
R.
Lehmann
,
I.
and
Vogeler
,
K.
, 2008, “
Periodical Unsteady Flow Within a Rotor Blade Row of an Axial Compressor. Part I: Flow Field at Midspan
,”
ASME J. Turbomach.
,
130
, p.
041004
.
15.
Mailach
,
R.
Lehmann
,
I.
and
Vogeler
,
K.
, 2008, “
Periodical Unsteady Flow Within a Rotor Blade Row of an Axial Compressor. Part II: Wake-Tip Clearance Vortex Interaction
,”
ASME J. Turbomach.
,
130
, p.
041005
.
16.
Mailach
,
R.
, 2001, “
Experimentelle Untersuchung von Strömungsinstabilitäten im Betriebsbereich zwischen Auslegungspunkt und Stabilitätsgrenze eines vierstufigen Niedergeschwindigkeits-Axialverdichters
,” Doctoral Thesis, TU Dresden.
17.
Suder
,
K. L.
, and
Celestina
,
M. L.
, 1996, “
Experimental and Computational Investigation of the Tip Clearance Flow in a Transonic Axial Compressor Rotor
,”
ASME J. Turbomach.
,
118
, pp.
218
229
.
18.
Michon
,
G.-J.
,
Miton
,
H.
, and
Ouayahya
,
N.
, 2005, “
Unsteady Off-Design Velocity and Reynolds Stresses in an Axial Compressor
,”
AIAA J. Propulsion Power
,
21
(
6
), pp.
961
972
.
19.
Ma
,
H.
,
Jiang
,
H.
, and
Zhang
,
Q.
, 2001, “
Three-Dimensional Unsteady Flow Field Due to IGV-Rotor Interaction in the Tip Region of an Axial Compressor Rotor Passage
,” ASME Paper No. 2001-GT-0296.
20.
Tisserant
,
D.
, and
Breugelmans
,
F. A. E.
, 1997, “
Rotor Blade-to-Blade Measurements Using Particle Image Velocimetry
,”
ASME J. Turbomach.
,
119
, pp.
176
181
.
21.
Balzani
,
N.
,
Scarano
,
F.
,
Riethmuller
,
M. L.
, and
Breugelmans
,
F. A. E.
, 2000, “
Experimental Investigation of the Blade-to-Blade Flow in a Compressor Rotor by Digital Particle Image Velocimetry
,”
ASME J. Turbomach.
,
122
, pp.
743
750
.
22.
Sanders
,
A. J.
,
Papalia
,
J.
, and
Fleeter
,
S.
, 2002, “
Multi-Blade Row Interactions in a Transonic Axial Compressor, Part I: Stator Particle Image Velocimetry (PIV) Investigations
,”
ASME J. Turbomach.
,
124
, pp.
10
18
.
23.
Liu
,
B.
,
Wang
,
H.
,
Liu
,
H.
,
Yu
,
H.
,
Jiang
,
H.
, and
Chen
,
M.
, 2004, “
Experimental Investigation of Unsteady Flow Field in the Tip Region of an Axial Compressor Rotor Passage at Near Stall Condition With Stereoscopic Particle Image Velocimetrie
,”
ASME J. Turbomach.
,
126
, pp.
360
374
.
24.
Voges
,
M.
,
Willert
,
C.
,
Mönig
,
R.
,
Müller
,
M. W.
, and
Schiffer
,
H.-P.
, 2010, “
The Challenge of Stereo PIV Measurements in the Tip Gap of a Transonic Compressor Rotor With Casing Treatment
,”
15th International Symposium on Applications of Laser Techniques to Fluid Mechanics
, No. 1.9.2 (
11
p.), Lisbon.
25.
Wernet
,
M. P.
,
Van Zante
,
D.
,
Strazisar
,
T. J.
,
John
,
W. T.
, and
Prahs
,
P. S.
, 2005, “
Characterization of the Tip Clearance Flow in an Axial Compressor Using 3-D Digital PIV
,”
Exp. Fluids
,
39
, pp.
743
753
.
26.
Fischer
,
A.
,
Büttner
,
L.
,
Czarske
,
J.
,
Eggert
,
M.
,
Grosche
,
G.
, and
Müller
,
H.
, 2007, “
Investigation of Time-Resolved Single Detector Doppler Global Velocimetry Using Sinusoidal Laser Frequency Modulation
,”
Meas. Sci. Technol.
,
18
, pp.
2529
2545
.
27.
Fischer
,
A.
,
Büttner
,
L.
,
Czarske
,
J.
,
Eggert
,
M.
, and
Müller
,
H.
, 2007, “
Measurements of Velocity Spectra Using Time-Resolving Doppler Global Velocimetry With Laser Frequency Modulation and a Detector Array
,”
Exp. Fluids
,
47
, pp.
599
611
.
28.
Fischer
,
A.
,
Büttner
,
L.
,
Czarske
,
J.
,
Eggert
,
M.
, and
Müller
,
H.
, 2009, “
Array Doppler Global Velocimeter With Laser Frequency Modulation for Turbulent Flow Analysis—Sensor Investigation and Application
,” in
Imaging Measurement Methods for Flow Analysis
,
W.
Nitsche
and
C.
Dobriloff
, eds.,
Springer
,
Berlin
, pp.
31
41
.
29.
Fischer
,
A.
,
Büttner
,
L.
,
Czarske
,
J.
,
Eggert
,
M.
, and
Müller
,
H.
, 2008, “
Measurement Uncertainty and Temporal Resolution of Doppler Global Velocimetry Using Laser Frequency Modulation
,”
Appl. Opt.
,
47
(
21
), pp.
3941
3953
.
30.
Fischer
,
A.
,
König
,
J.
, and
Czarske
,
J.
, 2008, “
Speckle Noise Influence on Measuring Turbulence Spectra Using Time-Resolved Doppler Global Velocimetry With Laser Frequency Modulation
,”
Meas. Sci. Technol.
,
19
, p.
125402
.
31.
Lakshminarayana
,
B.
, 1970, “
Methods of Predicting the Tip Clearance Effects in Axial Flow Turbomachinery
,”
ASME J. Basic Eng.
,
92
(
1
), pp.
467
482
.
32.
Williams
,
R.
,
Gregory-Smith
,
D.
,
He
,
L.
, and
Ingram
,
G.
, 2010, “
Experiments and Computations on Large Tip Clearance Effects in a Linear Cascade
,”
ASME J. Turbomach.
,
132
(
2
), pp.
18
21
.
33.
Clemen
,
C.
,
Gümmer
,
V.
,
Nerger
,
D.
, and
Saathoff
,
H.
, 2007, “
Investigation of Different Endwall Part-Clearance Configurations on a Low Speed Compressor Cascade
,”
7th European Turbomachinery Conference
,
Athens
,
Greece
.
34.
Saathoff
,
H.
, and
Stark
,
U.
, 1999, “
Endwall Boundary Layer Separation in a Single-Stage Axial-Flow Low-Speed Compressor and a High-Stagger Compressor Cascade
,”
Forsch. Ingenieurwesen
,
65
, pp.
217
224
.
You do not currently have access to this content.