A transient bulk flow model with circular whirl motion for rotordynamic coefficients of annular seals

Xia, Peng; Liu, Zhansheng; Yu, Xiangyu; Zhao, Jingming

doi:10.1016/j.cja.2018.02.011

Cited by 14 publications

(7 citation statements)

References 17 publications

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“…The rotordynamic coefficients of an HPTPB are important for the stability of high-speed rotating machines. Using the CFD-FSI model developed in this study, the harmonic identification method 32,33 is applied to evaluate the frequency-dependent dynamic coefficients in equation ( 3). The 1D rotor perturbation motion with multiple frequencies in the X-direction or Y-direction is defined by equations ( 11) and ( 12), which have proven to be accurate and efficient for evaluating rotordynamic coefficients.…”

Section: Harmonic Identification For Rotordynamic Coefficientsmentioning

confidence: 99%

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A novel transient computational fluid dynamics-fluid–structure interaction model for the pad adaptive motion and rotordynamic coefficients of hybrid porous tilting pad bearings

Xia,

Jin,

Song

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part J:

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Hybrid porous tilting pad bearings with the advantages of gas porous bearings and tilting pad bearings exhibited excellent rotor-supporting performance with high accuracy and stability. Under hybrid lubrication, the transient adaptive motion of the tilting pads was important for the rotordynamic characteristics. A novel fluid–structure interaction model of hybrid porous tilting pad bearings was developed to investigate the transient hydro forces and the pad's adaptive motion. The rotordynamic coefficients of the hybrid porous tilting pad bearings were identified using the rotor harmonic trajectory. The computational fluid dynamics-fluid–structure interaction model was validated with the experimental data. The effects of eccentricity ratios, rotor speeds, supply pressures, pivot radial stiffnesses, and dampings on the pad adaptive motion and the rotordynamic coefficients were evaluated. The pad self-adaption motions significantly influenced the supporting and vibration-absorbing characteristics of hybrid porous tilting pad bearings.

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Section: Harmonic Identification For Rotordynamic Coefficientsmentioning

confidence: 99%

“…26 With independent excitations in the X-direction and Y-direction, equation ( 3) is transformed into the complex frequency domain using a fast Fourier transform (FFT). 32…”

Section: Harmonic Identification For Rotordynamic Coefficientsmentioning

confidence: 99%

A novel transient computational fluid dynamics-fluid–structure interaction model for the pad adaptive motion and rotordynamic coefficients of hybrid porous tilting pad bearings

Xia,

Jin,

Song

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part J:

Self Cite

View full text Add to dashboard Cite

show abstract

“…Childs [3] applied finite-length solutions for the dynamic characteristics of an annular seal on the basis of the bulk flow model put forward by Black. This method has been widely used in engineering [4][5][6] due to its low computational cost and highly efficient computation time. Dietzen and Nordmann [7] first proposed the CFDperturbation method for smooth-rotor seals to improve the problem of the reliability of the bulk flow model.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Dynamic Characteristics of an Eccentric Annular Seal on the Basis of a Transient CFD Method with Three Whirl Models

Zhai

Cui

et al. 2021

JMSE

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Many annular seals suffer eccentricity because of rotor–stator misalignment or the deflection of a flexible rotor, which has a strong influence on the vibration characteristics and stability of rotating machines. In this article, a transient CFD method based on three whirl models is employed to research the dynamic characteristics of annular seals at various static eccentricities. The influence of the whirl amplitude on the dynamic characteristics of eccentric annular seals are also explored. The results of the transient CFD method are compared with the bulk flow model results and the experimental results. It is shown that the transient CFD method possesses high prediction precision for direct damping, with a maximum error of 25%. Negative kyx increases by 166% when the static eccentricity ratio is increased from 0 to 0.5. The dynamic characteristics of the annular seal operating at high static eccentric ratio are sensitive to whirl amplitude, and the model with an amplitude of 1% Cr has great advantages for the prediction of direct virtual-mass, while the model with an amplitude of 10% Cr has great advantages for the prediction of cross-coupled damping.

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“…The rotor dynamic coefficients have a nonlinear relationship with the eccentricity. With the increase of positive prewhirl at seal inlet, the crosscoupling stiffness increases gradually from negative to positive, and the rotor system is unstable [11]. However, a proper reverse prewhirl can enhance the rotor stability [12] and [13].…”

Section: Introductionmentioning

confidence: 99%

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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A transient bulk flow model with circular whirl motion for rotordynamic coefficients of annular seals

Cited by 14 publications

References 17 publications

A novel transient computational fluid dynamics-fluid–structure interaction model for the pad adaptive motion and rotordynamic coefficients of hybrid porous tilting pad bearings

A novel transient computational fluid dynamics-fluid–structure interaction model for the pad adaptive motion and rotordynamic coefficients of hybrid porous tilting pad bearings

Investigation of the Dynamic Characteristics of an Eccentric Annular Seal on the Basis of a Transient CFD Method with Three Whirl Models

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

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