In this paper we investigate the rotordynamics of a geared system with coupled lateral, torsional and axial vibrations, with a view toward understanding the severe vibration problems that occurred on a 28-MW turboset consisting of steam turbine, double helical gear and generator. The new dynamic model of the shaft line was based on the most accurate simulation of the static shaft lines, which are influenced by variable steam forces and load-dependent gear forces. The gear forces determine the static shaft position in the bearing shell. Each speed and load condition results in a new static bending line which defines the boundary condition for the dynamic vibration calculation of the coupled lateral, torsional and axial systems. Rigid disks and distributed springs were used for shaft line modeling. The tooth contact was modeled by distributed springs acting normally on the flank surfaces of both helices. A finite element method with distributed mass was used for lateral and torsional vibrations. It was coupled to a lumped mass model describing the axial vibrations. The forced vibrations due to unbalances and static transmission errors were calculated. The eigenvalue problem was solved by means of a stability analysis showing the special behavior of the coupled system examined. The calculation was successfully applied, and the source of the vibration problem could be located as being a gear-related transmission error. Several redesign proposals lead to a reliable and satisfactory vibrational behavior of the turboset.

1.
Blankenship
G.
Wesley
, and
Singh
R.
,
1995
Dynamic Force Transmissibility in Helical Gear Pairs
,”
Mech. Mach. Theory
, Vol.
30
, No.
3
, pp.
323
339
.
2.
Choy
F. K.
,
Tu
Y. K.
,
Zakrajsek
J. J.
, and
Townsend
D. P.
,
1991
, “
Effects of Gear Box Vibration and Mass Imbalance on the Dynamics of Multistage Gear Transmission
,”
ASME JOURNAL OF VIBRATION AND ACOUSTICS
, Vol.
113
, pp.
333
341
.
3.
Cleghorn
W. L.
, and
Tabarrok
B.
,
1992
, “
Finite Elements Formulation of a Tapered Timoshenko Beam for Free Lateral Vibration Analysis
,”
J. of Sound and Vibration
, Vol.
152
, No.
3
, pp.
461
470
.
4.
Han
D. C.
,
Choi
S. H.
, and
Lee
Y. H.
,
1995
, “
Analysis of Vibration Characteristics for a Rotor-Bearing System Using Distributed Spring and Damper Model
,”
Int. J. of Rotating Machinery
, Vol.
1
, No.
3–4
, pp.
277
284
.
5.
Han, D.-C., 1983, “Theoretische Ermittlung der Kennlinien und Stabilita¨tseigenschaften hochtouzriger Hybridlager,” Fortschritt-Bericht VDI, Reihe 1, Nr. 106.
6.
Hubensteiner, M., Urlichs, K., and Tinapp, J., 1994, “Schwingungsprobleme bei schnellaufenden Industriedampfturbinen,” VDI Berichte, NR. 1109, pp. 619–632.
7.
Iannuzzelli, Raymond J., and Elward, Robert M., 1984, “Torsional/Lateral Coupling in Geared Rotors,” ASME, 84-GT-71, pp. 1–8.
8.
Iida
H.
,
Tamura
A.
,
Kikuchi
K.
, and
Agata
H.
,
1980
, “
Coupled Torsional Flexural Vibration of a Shaft in a Geared System of Rotors
,”
Bulletins of JSME
, Vol.
23
, No.
186
, pp.
2111
2117
.
9.
Kahraman
A.
, Sep.
1994
, “
Dynamic Analysis of a Multi-Mesh Helical Gear Train
,”
ASME Journal of Mechanical Design
, Vol.
116
, pp.
706
712
.
10.
Kishor
B.
, and
Gupta
S. K.
,
1989
, “
On Dynamic Gear Tooth Loading Due to Coupled Torsional-Lateral Vibrations in a Geared Rotor-Hydrodynamic Bearing System
,”
ASME Journal of Tribology
, Vol.
111
, pp.
418
425
.
11.
Leonhard, M., and Kern, U., 1988, “Coupling of Lateral and Torsional Vibrations in Integrally Geared Turbo Compressors,” Proc. of the 2nd European Turbo-machinery Symposium, pp. 103–109.
12.
Mittwollen
N.
, and
Glienicke
J.
,
1990
, “
Operating Conditions of Multi-Lobed Journal Bearings Under High Thermal Loads
,”
ASME Journal of Tribology
, Vol.
112
, pp.
330
340
.
13.
Mittwollen
N.
,
Hegel
Th.
, and
Glienicke
J.
,
1991
, “
Effect of Hydrodynamic Thrust Bearings on Lateral Shaft Vibrations
,”
ASME Journal of Tribology
, Vol.
113
, pp.
811
818
.
14.
Nelson
H. D.
,
1980
, “
A Finite Rotating Shaft Element Using Timoshenko Beam Theory
,”
ASME Journal of Mechanical Design
, Vol.
106
, No.
4
, pp.
793
803
.
15.
Neriya
S. V.
,
Bhat
R. B.
, and
Sankar
T. S.
,
1984
, “
Effect of Coupled Torsional-Flexural Vibration of a Geared Shaft System on the Dynamic Tooth Load
,”
The Shock and Vibration Bulletin
, Part 3, Vol.
54
, pp.
67
75
.
16.
Rachel, J. D., and Szenasi, F. R., 1980, “Field Verification of Lateral-Torsional Coupling Effects on Rotor Instabilities in Centrifugal Compressors,” NASA Conf. Publication No. 2147.
17.
Schwibinger, P., Neumer, T., Ztuuml;bes, A., and Nordmann, R., 1988, “The Influence of Torsional-lateral-coupling in Geared Rotor Systems on its Eigenvalues, Modes and Unbalance Vibrations,” Proc. IMechE, C295/88, pp. 279–287.
18.
Simmos, H. R., and Smalley, A. J., 1984, “Lateral Gear Shaft Dynamics Control Torsional Stresses in Turbine Driven Compressor Train,” ASME, 84-GT-28.
19.
Zguven
H. N.
, and
Zkan
Z. L.
,
1984
, “
Whirl Speed and Unbalance Response of Multibearing Rotors Using Finite Elements
,”
ASME JOURNAL OF VIBRATION, ACOUSTICS, STRESS AND RELIABILITY IN DESIGN
, Vol.
106
, No.
1
, pp.
72
79
.
20.
Yamaha
T.
, and
Mist
J.
,
1979
, “
A Study on the Unstable Vibration Phenomena of a Reduction Gear System, Including the Lightly Loaded Journal Bearings, for a Marine Steam Turbine
,”
Bulletin of the JSME
, Vol.
22
, 1979, No.
163
, pp.
98
105
.
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