Three-Dimensional Computations of Rotordynamic Force Distributions in a Labyrinth Seal

Rhode, D. L.; Hensel, Steve J.; Guidry, M. J.

doi:10.1080/10402009308983184

Cited by 22 publications

(5 citation statements)

References 5 publications

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“…The static eccentricity of a rotor model is calculated with a steady-state solver, in which the rotor only has rotational motion. The results show that the radial and tangential steam flow exciting forces on rotor increase with the increase of eccentricity [9] and [10]. The rotor dynamic coefficients have a nonlinear relationship with the eccentricity.…”

Section: Introductionmentioning

confidence: 92%

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Cao

2020

SV-JME

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In order to study the steam flow excited vibration caused by the eccentricity of a rotor, three-dimensional rotor whirl motion is simulated based on mesh deformation. The mechanism of steam flow excited vibration and its influence on the dynamic characteristics of the rotor are investigated. The results show that the exciting forces change with the displacement of the rotor’s centre. Rotor dynamic coefficients are nonlinear when the rotor whirls pass the mesh deformation. The rotor dynamic coefficients and effective damping increase with the increase of whirl frequency. When the whirl frequency is 24.41 Hz, the rotor dynamic coefficients are strongly affected by rotational velocity. The maximum fluctuations of average direct stiffness, cross-coupling stiffness, direct damping and cross-coupling damping are 8.1 %, 113.2 %, 45.8 %, and 121.0 %, respectively. Effective damping fluctuates greatly when both whirl and rotational frequency are 24.41 Hz. The direct stiffness, direct damping, and effective damping increase with the increase of pressure ratio, which can improve rotor stability. The pressure fluctuation on the rotor’s surface is a primary reason for steam flow excited vibration. The stability margin of the rotor can be estimated precisely via effective damping.

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Section: Introductionmentioning

confidence: 92%

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Cao

2020

SV-JME

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“…Others have utilized the rapidly maturing computational fluid dynamic analysis for modeling annular seals including Dietzen and Nordman (1986), Rhode et al (1992), and Arghir and Frene (1997b). All of these authors employ a coordinate transformation from the 3D eccentric domain into a 2D axisymmetric one.…”

Section: Literature Reviewmentioning

confidence: 99%

CFD Comparison to 3D Laser Anemometer and Rotordynamic Force Measurements for Grooved Liquid Annular Seals

Moore

Palazzolo

1999

Journal of Tribology

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A pressure-based computational fluid dynamics (CFD) code is employed to calculate the flow field and rotordynamic forces in a whirling, grooved liquid annular seal. To validate the capabilities of the CFD code for this class of problems, comparisons of basic fluid dynamic parameters are made to three-dimensional laser Doppler anemometer (LDA) measurements for a spinning, centered grooved seal. Predictions are made using both a standard and low Reynolds number κ-ε turbulence model. Comparisons show good overall agreement of the axial and radial velocities in the through flow jet, shear layer, and recirculation zone. The tangential swirl velocity is slightly under-predicted as the flow passes through the seal. By generating an eccentric three-dimensional, body fitted mesh of the geometry, a quasi-steady solution may be obtained in the whirling reference frame allowing the net reaction force to be calculated for different whirl frequency ratios, yielding the rotordynamic force coefficients. Comparisons are made to the rotordynamic force measurements for a grooved liquid annular seal. The CFD predictions show improved stiffness prediction over traditional multi-control volume, bulk flow methods over a wide range of operating conditions. In cases where the flow conditions at the seal inlet are unknown, a two-dimensional, axisymmetric CFD analysis may be employed to efficiently calculate these boundary conditions by including the upstream region loading to the seal. This approach is also demonstrated in this study.

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“…The three-dimensional unsteady numerical simulation method was adopted by Luan et al [16,17] to study the flow field in the blade tip clearance and the spectral characteristics of leakage vortexes in the seal cavity. An eccentric, single labyrinth cavity was investigated on three different inlet swirl conditions and the effect of inlet swirl on the pressure distribution of the shroud surfaces was analyzed [18], while the influence of leakage vortexes on the pressure distribution of the shroud surfaces was not analyzed in the previous research. Leong and Brown [19] pointed out that the circumferential pressure distribution was nearly uniform on concentric condition while it exhibited a nearly cosinoidal distribution on the eccentric condition.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis on Steam Exciting Force Caused by Rotor Eccentricity

Cao

Wang

et al. 2017

Shock and Vibration

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The steam exciting force has been proved to be great threat to the operation safety of steam turbines. The mechanism of steam exciting vibration cannot be profoundly revealed by simply analyzing the steam exciting force, especially in simplified models. Therefore, a full-circle stage of steam turbine with shroud and labyrinth seals was investigated by numerical simulator CFX. The instability of leakage flow and the pressure fluctuation were analyzed on the eccentric condition. The effects of leakage vortexes, the depth-width ratio of seal cavity, and the eccentricity on the steam exciting force were studied. Results show that the leakage flow is nonuniform in the circumferential direction with the change of front teeth vortexes, which causes the steam exciting force. The tangential and radial steam exciting force both increase with the eccentricity increasing. The effects of the depth-width ratio of seal cavity on the two forces are different. In addition, the pressure fluctuation caused by the leakage vortexes on the shroud surfaces is a main factor inducing the steam exciting force. This research provides a theoretical guidance for the operation safety and optimization of steam turbines.

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Three-Dimensional Computations of Rotordynamic Force Distributions in a Labyrinth Seal

Cited by 22 publications

References 5 publications

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

Dynamic Characteristics and Stability Prediction of Steam Turbine Rotor Based on Mesh Deformation

CFD Comparison to 3D Laser Anemometer and Rotordynamic Force Measurements for Grooved Liquid Annular Seals

Numerical Analysis on Steam Exciting Force Caused by Rotor Eccentricity

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