This paper addresses the unsteady formation of secondary flow structures inside a turbine rotor passage. The first stage of a two-stage, low-pressure turbine is investigated at a Reynolds Number of 75,000. The design represents the third and the fourth stages of an engine-representative, low-pressure turbine. The flow field inside the rotor passage is discussed in the relative frame of reference using the streamwise vorticity. A multistage unsteady Reynolds-averaged Navier–Stokes (URANS) prediction provides the time-resolved data set required. It is supported by steady and unsteady area traverse data acquired with five-hole probes and dual-film probes at rotor inlet and exit. The unsteady analysis reveals a nonclassical secondary flow field inside the rotor passage of this turbine. The secondary flow field is dominated by flow structures related to the upstream nozzle guide vane. The interaction processes at hub and casing appear to be mirror images and have characteristic forms in time and space. Distinct loss zones are identified, which are associated with vane-rotor interaction processes. The distribution of the measured isentropic stage efficiency at rotor exit is shown, which is reduced significantly by the secondary flow structures discussed. Their impacts on the steady as well as on the unsteady angle characteristics at rotor exit are presented to address the influences on the inlet conditions of the downstream nozzle guide vane. It is concluded that URANS should improve the optimization of rotor geometry and rotor loss can be controlled, to a degree, by nozzle guide vane (NGV) design.

References

References
1.
Langston
,
L. S.
,
2001
, “
Secondary Flows in Axial Turbines—A Review
,”
Ann. N.Y. Acad. Sci.
,
934
(
1
), pp.
11
26
.10.1111/j.1749-6632.2001.tb05839.x
2.
Sharma
,
O. P.
, and
Butler
,
T. L.
,
1987
, “
Predictions of Endwall Losses and Secondary Flows in Axial Flow Turbine Cascades
,”
ASME J. Turbomach.
,
109
, pp.
229
236
.10.1115/1.3262089
3.
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
,
107
, pp.
248
257
.10.1115/1.3239704
4.
Schinko
,
N.
,
2012
, “
Verfahren zur Optimierung von Zwei-Dimensionalen Strömungsberechnungen Während der Turbinenerprobung
,” Ph.D. thesis, Faculty Aerospace Engineering and Geodesy, University of Stuttgart, Stuttgart, Germany.
5.
Nitsche
,
W.
, and
Brunn
,
A.
,
2006
,
Strömungsmesstechnik
, Springer, Berlin.
6.
Bearman
,
P. W.
,
1971
, “
Correction for the Effect of Ambient Temperature Drift on Hot-Wire Measurements in Incompressible Flow
,” DISA Information No. 11, pp.
25
30
.
7.
Kürner
,
M.
,
Rose
,
M. G.
,
Staudacher
,
S.
,
Gier
,
J.
,
Fiala
,
A.
, and
Patzer
,
B.
,
2012
, “
Surface Thin Film Gauge Measurements in a Two-Stage Low Pressure Turbine at Low Reynolds Number
,”
ASME
Paper No. GT2012-68906.10.1115/GT2012-68906
8.
Kürner
,
M.
,
Schneider
,
C.
,
Rose
,
M. G.
,
Staudacher
,
S.
, and
Gier
,
J.
,
2010
, “
LP Turbine Reynolds Lapse Phenomena: Time-Averaged Area Traverse and Multi-stage CFD
,”
ASME
Paper No. GT2010-23114.10.1115/GT2010-23114
9.
Röber
,
T.
,
Kozulovic
,
D.
,
Kügeler
,
E.
, and
Nürnberger
,
D.
,
2006
, “
Appropriate Turbulence Modeling for Turbomachinery Flows Using a Two-Equation Turbulence Model
,”
New Results Numer. and Exp. Fluid Mech. V
,
92
, pp.
446
454
.10.1007/978-3-540-33287-9
10.
Kürner
,
M.
,
Reichstein
,
G. A.
,
Schrack
,
D.
,
Rose
,
M. G.
,
Staudacher
,
S.
,
Gier
,
J.
, and
Engel
,
K.
,
2011
, “
LP Turbine Secondary Vortices: Reynolds Lapse
,”
ASME
Paper No. GT2011-45557.10.1115/GT2011-45557
11.
Niehuis
,
R.
,
Lücking
,
P.
, and
Stubert
,
B.
,
1990
, “
Experimental and Numerical Study on Basic Phenomena of Secondary Flows in Turbines
,”
AGARD Conf. Proc. No. 469
, pp.
5.1
5.17
.
12.
Greitzer
,
E. M.
,
Tan
,
C. S.
, and
Graf
,
M. B.
,
2004
,
Internal Flow—Concepts and Applications
,
Cambridge University Press
,
Cambridge, England
.
13.
Binder
,
A.
, and
Romey
,
R.
,
1983
, “
Secondary Flow Effects and Mixing of the Wake Behind a Turbine Stator
,”
ASME J. Eng. Power
,
105
, pp.
40
46
.10.1115/1.3227396
14.
Rose
,
M. G.
,
2010
, “
Unsteady Flows in Axial Turbines
,” Habilitation thesis, University of Stuttgart, Stuttgart, Germany.
15.
Gostelow
,
J. P.
,
1977
, “
A New Approach to the Experimental Study of Turbomachinery Flow Phenomena
,”
ASME J. Eng. Power
,
99
, pp.
97
105
.10.1115/1.3446259
16.
Hawthorne
,
W. R.
,
1955
, “
Rotational Flow Through Cascades—Part I. The Components of Vorticity
,”
Q. J. Mech. Appl. Math.
,
8
, pp.
266
279
.10.1093/qjmam/8.3.266
17.
Pullan
,
G.
,
Denton
,
J.
, and
Dunkley
,
M.
,
2003
, “
An Experimental and Computational Study of the Formation of a Streamwise Shed Vortex in a Turbine Stage
,”
ASME J. Turbomach.
,
125
, pp.
291
297
.10.1115/1.1545766
18.
Binder
,
A.
,
Schroeder
,
Th.
, and
Hourmouziadis
,
J.
,
1989
, “
Turbulence Measurements in a Multistage Low-Pressure Turbine
,”
ASME J. Turbomach.
,
111
, pp.
153
161
.10.1115/1.3262250
19.
Binder
,
A.
,
1985
, “
Turbulence Production Due to Secondary Vortex Cutting in a Turbine Rotor
,”
ASME J. Eng. Gas Turbines Power
,
107
, pp.
1039
1046
.10.1115/1.3239808
20.
Aurahs
,
L.
,
Kasper
,
C.
,
Kürner
,
M.
,
Rose
,
M. G.
,
Staudacher
,
S.
, and
Gier
,
J.
,
2009
, “
Water Flow Model Turbine Flow Visualization Study of the Unsteady Interaction of Secondary Flow Vortices With the Downstream Rotor
,”
J. Power Energy
,
223
(
6
), pp.
677
686
.10.1243/09576509JPE841
21.
Schneider
,
C. M.
,
Schrack
,
D.
,
Rose
,
M. G.
,
Staudacher
,
S.
,
Guendogdu
,
Y.
, and
Engel
,
K.
,
2013
, “
On the Interaction of Streamwise Vorticity With a Rotating Turbine Blade
,”
10th European Turbomachinery Conference
, Lappeenranta, Finland, April 15–19.
22.
Denton
,
J.
, and
Pullan
,
G.
,
2012
, “
A Numerical Investigation Into the Sources of Endwall Loss in Axial Flow Turbines
,”
ASME
Paper No. GT2012-69173.10.1115/GT2012-69173
23.
Germain
,
T.
,
Nagel
,
M.
,
Raab
,
I.
,
Schüpbach
,
P.
,
Abhari
,
R. S.
, and
Rose
,
M. G.
,
2010
, “
Improving Efficiency of a High Work Turbine Using Nonaxisymmetric Endwalls—Part I: Endwall Design and Performance
,”
ASME J. Turbomach.
,
132
, p.
021007
.10.1115/1.3106706
24.
Cerretelli
,
C.
, and
Williamson
,
C. H. K.
,
2003
, “
The Physical Process of Vortex Merging
,”
J. Fluid Mech.
,
475
, pp.
41
77
.10.1017/S0022112002002847
25.
Hodson
,
H. P.
, and
Dominy
,
R. G.
,
1987
, “
The Off-Design Performance of a Low-Pressure Turbine Cascade
,”
ASME J. Turbomach.
,
109
, pp.
201
209
.10.1115/1.3262086
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