This paper presents an experimental investigation of the vane-blade unsteady interaction in an unshrouded low pressure (LP) turbine research rig with uneven blade/vane count (72 blades and 96 vanes). The rig was designed in cooperation with MTU Aero Engines and considerable efforts were put on the adjustment of all relevant model parameters. In particular blade count ratio, airfoil aspect ratio, reduced mass flow, reduced speed, and Mach and Reynolds numbers were chosen to reproduce the full scale LP turbine at take off condition. Measurements by means of a fast-response pressure probe were performed adopting a phase-locked acquisition technique in order to provide the time resolved flow field downstream of the turbine rotor. The probe has been fully traversed both in circumferential and radial traverses. The rotor exit is characterized by strong perturbations due to the tip leakage vortex and the rotor blade wake. Circumferential nonuniformities due to the upstream vane wake and to the downstream exit guide vane potential effects are also identified. Furthermore, in the present configuration with an uneven blade/vane count the nonuniformities due to the stator and rotor row are misaligned along the whole turbine circumference and create a spinning mode that rotates in direction opposite to the rotor at a high frequency. The aeroacoustic theory is employed to explain such further unsteady pattern. The variations of the exit flow angle within a cycle of such pattern are not negligible and almost comparable to the ones within the blade passing period.

References

References
1.
Binder
,
A.
,
Förster
,
W.
,
Kruse
,
H.
, and
Rogge
,
H.
, 1985, “
Experimental Investigation Into the Effect of Wakes on the Unsteady Turbine Rotor Flow
,”
ASME J. Eng. Gas Turbines Power
,
107
(
2
), pp.
458
465
.
2.
Hodson
,
H. P.
, 1985, “
Measurements of Wake-Generated Unsteadiness in the Rotor Passages of Axial Flow Turbines
,”
ASME J. Eng. Gas Turbines Power
,
107
(
2
), pp.
467
476
.
3.
Sharma
,
O. P.
,
Pickett
,
G. F.
, and
Ni
,
R. H.
, 1992, “
Assessment of Unsteady Flows in Turbines
,”
ASME J. Turbomach.
,
114
, pp.
79
90
.
4.
Pullan
,
G.
, 2006, “
Secondary Flows and Loss Caused By Blade Row Interaction in a Turbine Stage
,”
ASME J. Turbomach.
,
128
, pp.
484
491
.
5.
Persico
,
G.
,
Mora
,
A.
,
Gaetani
,
P.
, and
Savini
,
M.
, 2010, “
Unsteady Aerodynamics of a Low Aspect Ratio Turbine Stage: Modeling Issues and Flow Physics
,”
Proceedings of ASME Turbo Expo 2010
, June 14–18,
Glasgow, UK
, ASME Paper No. GT2010-22927.
6.
Arndt
,
N.
, 1993, “
Blade Row Interaction in a Multistage Low-Pressure Turbine
,”
ASME J. Turbomach.
,
115
, pp.
137
146
.
7.
Korakianitis
,
T.
, 1992, “
Blade-Loading Effects on the Propagation of Unsteady Flow and on Forcing Functions in Axial-Turbine Cascades
,”
J. Phys. III
,
2
(
2
), pp.
507
525
.
8.
Hodson
,
H. P.
, and
Howell
,
R. J.
, 2005, “
The Role of Transition in High Lift Low Pressure Turbines for Aero Engines
,”
Progress Aerospace Sci.
,
41
(
6
), pp.
419
454
.
9.
Groeneweg
,
J. F.
,
Sofrin
,
T. G.
,
Rice
,
E. J.
, and
Gliebe
,
P. R.
, 1991, “
Turbomachinery Noise
,”
Aeroacoustics of Flight Vehicles: Theory and Practice, Vol. 1: Noise Sources
,
H.
Hubbard
, ed., NASA RP-1258, pp.
151
209
.
10.
Tyler
,
J.
, and
Sofrin
,
T.
, “
Axial Flow Compressor Noise Studies
,”
SAE Technical Paper 620532
, 1962,
70
, pp.
309
332
.
11.
Rienstra
,
S. W.
, and
Hirschberg
,
A.
, 2004,
An Introduction to Acoustics,
Eindhoven University of Technology
.
12.
Arnone
,
A.
, and
Pacciani
,
R.
, 1996, “
Rotor-Stator Interaction Analysis Using the Navier-Stokes Equation and a Multigrid Method
,”
ASME J. Turbomach.
,
118
, pp.
679
689
.
13.
Dorney
,
D. J.
,
Flitan
,
H. C.
,
Ashpis
,
D. E.
, and
Solomon
,
W. J.
, 2000, “
The Effects of Blade Count on Boundary Layer Development in a Low-Pressure Turbine
,”
38th Aerospace Sciences Meeting and Exhibit
,
Reno, Nevada
, January 10–13, Paper No. AIAA-2000-0742.
14.
Gerolymos
,
G. A.
,
Michon
,
G. J.
, and
Neubauer
,
J.
, 2002, “
Analysis and Application of Chorochronic Periodicity in Turbomachinery Rotor/Stator Interaction Computations
,”
J. Propulsion Power
,
18
(
6
), pp.
1139
1152
.
15.
Moser
,
M.
,
Tapken
,
U.
,
Enghardt
,
L.
, and
Neuhaus
,
L.
, 2009, “
An Investigation of Low Pressure Turbine Blade-Vane Interaction Noise: Measurements in a 1.5-Stage Rig
,”
Proc. Inst. Mech. Eng. Part A
,
223
(
6
), pp.
687
695
.
16.
Moser
,
M.
,
Kahl
,
G.
,
Kulhanek
,
G.
, and
Heitmeir
,
F.
, 2007, “
Construction of a Subsonic Test Turbine Facility for Experimental Investigations of Sound Generation and Propagation For Low Pressure Turbines
,” ISABE Conference Beijing, Paper No. ISABE-2007-1366.
17.
Persico
,
G.
,
Gaetani
,
P.
, and
Guardone
,
A.
, 2005, “
Design and Analysis of New Concept Fast-Response Pressure Probes
,”
Meas. Sci. Technol.
,
16
, pp.
1741
1750
.
18.
Enghardt
,
L.
,
Tapken
,
U.
,
Neise
,
W.
,
Kennepohl
,
F.
, and
Heinig
,
K.
, 2001, “
Turbine Blade/Vane Interaction Noise: Acoustic Mode Analysis Using In-Duct Sensor Rakes
,”
Proceedings of the Seventh AIAA/CEAS-Aeroacoustics Conference
,
Maastricht, The Netherlands
,
28
30
May, Paper No. 2001-2153.
19.
Gaetani
,
P.
,
Persico
,
G.
,
Dossena
,
V.
, and
Osnaghi
,
C.
, 2007, “
Investigation of the Flow Field in a High-Pressure Turbine Stage for Two Stator-Rotor Axial Gaps—Part 2: Unsteady Flow Field
,”
ASME J. Turbomach.
,
129
, pp.
580
590
.
20.
Bindon
,
J. P.
, 1989, “
The Measurement and Formation of Tip Leakage Loss
,”
ASME J. Turbomach.
,
111
, pp.
257
263
.
21.
Arts
,
T.
, Ed., 2004, Turbine Blade Tip Design and Tip Clearance Treatment, (VKI Lecture Series LS 2004-02), von Karman Institute.
22.
Miller
,
R. J.
,
Moss
,
R. W.
,
Ainsworth
,
R. W.
, and
Harvey
,
N. W.
, 2003, “
The Development of Turbine Exit Flow in a Swan-Necked Inter-Stage Diffuser
,”
Proceedings of ASME Turbo Expo 2003
, June 16–19,
Atlanta, GA
, ASME Paper No. GT-2003-38174.
23.
Binder
,
A.
,
Schröder
,
T.
, and
Hourmouziadis
,
J.
, 1989, “
Turbulence Measurements in a Multistage Low-Pressure Turbine
,”
ASME J. Turbomach.
,
111
(
2
), pp.
153
161
.
24.
Eversman
,
W.
, 1991, “
Theoretical Models for Duct Acoustic Propagation and Radiation
,”
Aeroacoustics of Flight Vehicles: Theory and Practice, Vol. 2: Noise Control
,
H.
Hubbard
, ed., NASA RP-1258, pp.
101
163
.
25.
Canepa
,
E.
,
Formosa
,
P.
,
Lengani
,
D.
,
Simoni
,
D.
,
Ubaldi
,
M.
, and
Zunino
,
P.
, 2007, “
Influence of Aerodynamic Loading on Rotor-Stator Aerodynamic Interaction in a Two-Stage Low Pressure Research Turbine
,”
ASME J. Turbomach.
,
129
, pp.
725
732
.
26.
Miller
,
R. J.
,
Moss
,
R. W.
,
Ainsworth
,
R. W.
, and
Harvey
,
N. W.
, 2004, “
The Effect of an Upstream Turbine on a Low-Aspect Ratio Vane
,”
Proceedings of ASME Turbo Expo 2004
, June 14–17,
Vienna, Austria
, ASME Paper No. GT-2004-54017.
27.
Zaccaria
,
M. A.
, and
Lakshminarayana
,
B.
, 1997, “
Unsteady Flow Field Due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part 1—Rotor Passage Flow Field
,”
ASME J. Turbomach.
,
119
, pp.
201
213
.
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