Dynamic analysis and identification of unbalance and misalignment in a rigid rotor with two offset discs levitated by active magnetic bearings: a novel trial misalignment approach

Kumar, Prabhat; Tiwari, Rajiv

doi:10.1016/j.jppr.2020.06.003

Cited by 27 publications

(4 citation statements)

References 29 publications

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“…where F sh represents the generalized external force. Substituting Equations ( 8) and (10) into Equation (11) and the left-hand side becomes d dt (12) where M sh , C sh (t) and K sh are the mass, damping, and stiffness matrix for the shaft element; F sh (t) and F sh,ds (t) are the additional force resulting from rotor acceleration and the drill-string motion. It is important to note that the theoretical derivation relies on a significant number of simplifications and assumptions.…”

Section: Shaft Element Modelmentioning

confidence: 99%

See 1 more Smart Citation

Study on Rotor-Bearing System Vibration of Downhole Turbine Generator under Drill-String Excitation

Yao,

Tian,

Zhan

et al. 2024

Energies

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Downhole turbine generators (DHTG) installed within drill-string are susceptible to internal and external excitation during the drilling process, causing significant dynamic loads on bearings, and thereby reducing the bearing’s service life. In this study, a finite element model of an unbalanced rotor-bearing system (RBS) of DHTG with multi-frequency excitations, based on the Lagrangian motion differential equation, is established. The responses of the RBS under different drill-string excitations in terms of time-domain response, whirl orbit, and spectrum are analyzed. For a constant rotor speed, lateral harmonic translational and lateral oscillation both transform the whirl orbit to quasi-periodic, while axial rotation only changes the response amplitude. Changing the duration of pulse excitation leads to different response forms. Then, the dynamic characteristics of the RBS supported by a squeeze film damper (SFD) are investigated. The results indicate that SFD effectively reduces the displacement response amplitude and bearing force near the critical speed. As the axial rotation angular velocity of the drill-string increases, the first critical speed and displacement response decrease, while the variation of lateral oscillation frequency and amplitude has limited impact on them. The established model provides a means for analyzing the dynamic characteristics of DHTG’s RBS under drill-string excitations during the design stage.

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Section: Shaft Element Modelmentioning

confidence: 99%

“…They provided numerical and experimental analyses of the transient response of the model. Kumar and Tiwari [12] developed an identification algorithm for the unbalanced rotor model supported by active magnetic bearings. They utilized FFT to estimate the eccentricity and constant force of the bearing based on response harmonics.…”

Section: Introductionmentioning

confidence: 99%

Study on Rotor-Bearing System Vibration of Downhole Turbine Generator under Drill-String Excitation

Yao,

Tian,

Zhan

et al. 2024

Energies

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“…Kumar and Tiwari [19] showed the identification of a system with two radial bearings to support the rotor. In [20], for the misalignment identification, a trial misalignment approach was proposed. Srinivas et al [10] used an auxiliary AMB for fault identification and analysis of dual-coupled Jeffcott rotors supported by rolling-element bearings.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a High-Power AMB–Multirotor Drivetrain

Jastrzebski,

Putkonen,

Zhuravlev

et al. 2024

IEEE Trans. Ind. Electron.

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Active magnetic bearings are commonly applied in high-speed rotors in the medium to high power range to replace rolling-element or oil-film bearings. They require less maintenance and provide a number of unique benefits owing to their contactless suspension and active control. A rotor construction with integrated compressors or turbines results in predictable and controllable rotor dynamics, where model-based controllers can be used. Model-based centralized controllers outperform decoupled transfer function controllers, but they require accurate plant models. For integrated impellers on a single rotor, the control models comprise a rigid rotor and the lowest frequency bending modes. The bending mode frequency and parameters related to node locations can be identified, yielding controllers tuned to the application. This work introduces drivetrain modeling and magnetic levitation control of a 2 MW rotor and an external load attached to the electric machine rotor with a radially stiff but flexural coupling. The model-based control is tested in an experimental setup, and the drivetrain frequency responses are compared with the modeled multirotor drivetrain dynamics.

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“…The related studies included [15] where multiple active magnetic bearings was utilized, however, the identification algorithm was demonstrated with two radial AMBs supporting single rotor. In [16] a trial misalignment approach for misalignment identification was proposed. In [17] two coupled Jeffcott rotors, supported with rolling element bearings and an auxiliary AMBs for fault identification were analyzed.…”

Section: Introductionmentioning

confidence: 99%