The unsteady flow phenomenon (identified as rotating instability) in the last stage of a low-pressure model steam turbine operated at very low mass flow conditions is numerically studied. This kind of instability has been observed previously in compressors and can be linked to the high structural stress levels associated with flow-induced blade vibrations. The overall objective of the study is to enhance the understanding of the rotating instability in steam turbines at off design conditions. A numerical analysis using a validated unsteady nonlinear time-domain CFD solver is performed. The 3D solution captures the massively separated flow structure in the rotor-exhaust region and the pressure ratio characteristics around the rotor tip of the test model turbine stage in good comparison with the experiment. A computational study with a multi-passage whole annulus domain on two different 2D blade sections is subsequently carried out. The computational results clearly show that a rotating instability in a turbine blading configuration can be captured by the 2D model. The frequency and spatial modal characteristics are analyzed. The simulations seem to be able to predict a rotating fluid dynamic instability with the similar characteristic features to those of the experiment. In contrast to many previous observations, the results for the present configurations suggest that the onset and development of rotating instabilities can occur without 3D and tip-leakage flows, although a quantitative comparison with the experimental data can only be expected to be possible with fully 3D unsteady solutions.

References

References
1.
Day
,
I. J.
,
1993
, “
Stall Inception in Axial Flow Compressors
,”
ASME J. Turbomach.
,
115
(
1
), pp.
1
9
.10.1115/1.2929209
2.
He
,
L.
,
1997
, “
Computational Study of Rotating Stall Inception in Axial Compressors
,”
AIAA J. Propul. Power
,
13
(
1
), pp.
31
38
.10.2514/2.5147
3.
Hah
,
C.
,
Schulze
,
R.
,
Wagner
,
S.
, and
Hennecke
,
D. K.
,
1999
, “
Numerical and Experimental Study for the Short Wavelength Stall Inception in a Low-Speed Axial Compressor
,”
Proceedings of the Fourteenth ISABE Conference, Florence, Italy, September 5–10, ISABE Paper No. 99-7033
.
4.
He
,
L.
, and
Ismael
,
J. O.
,
1999
, “
Computations of Blade Row Stall Inception in Transonic Flows
,”
Aeronaut. J.
,
103
(
1025
), pp.
317
324
.
5.
Bent
,
P. H.
,
McLaughlin
,
D. K.
, and
Thompson
,
D. E.
,
1992
, “
The Influence of Discharge Configuration on the Generation of Broadband Noise in Centrifugal Turbomachinery
,”
D. DGLR/AIAA Paper No. 92-02-099
.
6.
Mongeau
,
L.
, and
Quinlan
,
D. A.
,
1992
, “
An Experimental Study of Broadband Noise Sources in Small Axial Fans
,”
Proceedings of the International Symposium on Fan Noise INCE, Senlis
,
France
.
7.
Mongeau
,
L.
,
Thompson
,
D. E.
, and
McLaughlin
,
D. K.
,
1993
, “
Sound Generation by Rotating Stall in Centrifugal Turbomachines
,”
J. Sound Vib.
,
163
(
1
), pp.
1
30
.10.1006/jsvi.1993.1145
8.
Cumpsty
,
N. A.
,
2004
,
Compressor Aerodynamics 2nd ed.
,
Krieger Publishing Company
,
Malabar
,
FL
.
9.
Gerschütz
,
W.
,
Casey
,
M.
, and
Truckenmüller
,
F.
, 2005, “
Experimental Investigations of Rotating Flow Instabilities in the Last Stage of a Low-Pressure Model Steam Turbine During Windage
,”
Proc. IMechE, Part A: J. Power Energy
,
219
, pp.
499
510
.10.1243/095765005X31379
10.
Hah
,
C.
,
Voges
,
M.
,
Mueller
,
M.
, and
Schiffer
,
H. P.
,
2010
, “
Characteristics of Tip Clearance Flow Instability in a Transonic Compressor
,” Proceedings of ASME Turbo Expo 2010: Power for Land, Sea and Air (GT2010),
Glasgow, UK
, June 14–18,
ASME
Paper No. GT2010-22101, pp.
63
74
. 10.1115/GT2010-22101
11.
März
,
J.
,
Hah
,
C.
, and
Neise
,
W.
,
2002
, “
An Experimental and Numerical Investigation into the Mechanisms of Rotating Instability
,”
ASME J. Turbomach.
,
124
(3)
, pp.
367
374
. 10.1115/1.1460915
12.
Vo
,
H. D.
,
2010
, “
Role of Tip Clearance Flow in Rotating Instabilities and Nonsynchronous Vibrations
,”
J. Propul. Power
,
26
(
3
), pp.
556
561
.10.2514/1.26709
13.
Kameier
,
F.
, and
Neise
,
W.
,
1997
, “
Rotating Blade Flow Instability as a Source of Noise in Axial Turbomachines
,”
J. Sound Vib.
,
203
(
5
), pp.
833
853
.10.1006/jsvi.1997.0902
14.
Liu
,
J. M.
,
Holste
,
F.
, and
Neise
,
W.
,
1996
, “
On the Azimuthal Mode Structure of Rotating Blade Flow Instabilities in Axial Turbomachines
,”
AIAA Meeting Papers on Disc, A9630853, AIAA Paper No. 96-1741
.
15.
Baumgartner
,
M.
,
Kameier
,
F.
, and
Hourmouziadis
,
J.
,
1995
, “
Non-Engine Order Blade Vibration in a High Pressure Compressor
,”
Proceedings of the ISABE-Twelfth International Symposium on Airbreathing Engines, Melbourne
,
Australia
,
September 10-15
.
16.
Sparlart
,
P. R.
, and
Allmaras
,
S. R.
,
1992
, “
A One-Equation Turbulence Model for Aerodynamic Flows
,”
AIAA Paper No. 92-0439
.
17.
Jameson
,
A.
,
Schmidt
,
W.
, and
Turkel
,
E.
,
1981
, “
Numerical Solutions of the Euler Equation by Finite Volume Method Using Runge-Kutta Time-Stepping Scheme
,”
AIAA Paper No. 81-1259
.
18.
He
,
L.
,
2000
, “
3-D Navier-Stokes Analysis of Rotor-Stator Interactions in Axial-Flow Turbines
,”
Proc. IMech. E, Part A
,
214
(
1
), pp.
13
22
.10.1243/0957650001537813
19.
He
,
L.
,
1998
, “
Unsteady Flow in Oscillating Turbine Cascades
,”
ASME J. Turbomach.
,
120
(
2
), pp.
262
275
.10.1115/1.2841401
20.
Truckenmüller
,
F.
,
2002
, “
Untersuchungen zur aerodynamisch induzierten Schwingungsanregung von Niederdruck- Laufschaufeln bei extremer Teillastt
,”
Ph.D. thesis
,
University of Stuttgart
,
Stuttgart, Germany
.
21.
Denton
,
J. D.
,
1992
, “
The Calculation of Three-Dimensional Viscous Flow Through Multistage Turbomachine
,”
ASME J. Turbomach.
,
114
(
1
), pp.
18
26
.10.1115/1.2927983
You do not currently have access to this content.