Eigen and temporal characteristics of multi-frequency parametrically-excited rotor-oscillator systems

Anilkumar, Allen; Kartik, V.

doi:10.1016/j.jsv.2020.115824

Cited by 7 publications

(2 citation statements)

References 32 publications

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“…However, equations of motion for the general rotor subject to harmonic follower force will have periodic coefficients with two frequencies, associated with exciting frequency with period of 2π/normalΩext, and rotational speed with period of π/Ω, regardless of the used coordinate system. The overall period in this case is the “least common multiplier” (LCM) between the two periods (Anilkumar and Kartik, 2021a; 2021b), which will be used in stability analysis based on Floquet’s theory.…”

Section: Resultsmentioning

confidence: 99%

Stability of general asymmetric-anisotropic rotors subject to harmonic follower force

Khader

Magableh

2022

Journal of Vibration and Control

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The presented work examines the stability of general rotors subject to harmonic follower force. The examined rotor consists of asymmetric Timoshenko shaft carrying asymmetric rigid disk and supported by anisotropic flexible bearings. The assumed modes method is combined with Lagrange’s equation to derive the governing equations of motion with the help of symbolic computation. The employed approach resulted in equations of motion with multi-frequency periodic coefficients, and Floquet’s method was used to determine stability boundaries of the considered rotors. After validation of the proposed mathematical model, it was employed to examine the combined effect of rotor asymmetry, support anisotropy, and rotor speed on its stability in the presence of harmonic follower force. The presented results show that the considered general rotor exhibits both subharmonic and combination instabilities, which were completely identified and investigated. Additional higher order subharmonic and combination instabilities are observed for general rotors only.

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Section: Resultsmentioning

confidence: 99%

Stability of general asymmetric-anisotropic rotors subject to harmonic follower force

Khader

Magableh

2022

Journal of Vibration and Control

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“…time-domain information of the lift coefficient obtained by the simulation of the transient flow field [18]. The lift coefficient expression is [4]:…”

Section: Plos Onementioning

confidence: 99%

Evaluation the possibility of vortex-induced resonance for a multistage pressure reducing valve

Chen

Liu

et al. 2022

PLoS ONE

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A multistage pressure reducing valve is presented in this paper. The pressure reducing components are specially designed to not only control the flow rate but also effectively prevent the cavitation vibration. However, when the fluid flows through the pressure reducing components, the divergence and shedding of the vortices in the flow field seriously affect the stability of the valve and cause vortex-induced vibration. Especially, the main frequency of the vortex shedding is in the same frequency range as the modal frequency of the valve, the vortex-induced resonance of the valve occurs. It seriously affects the safety of a control system. In this paper, by monitoring the lift coefficient of the vortex cross flow in the valve, the frequency spectrum information of the lift coefficient is used as the novelty indexes to indicate vortex-induced vibration of the fluid in the valve. The main frequency and amplitude of vortex-induced vibration are obtained. The factors affecting the vortex-induced vibration of the fluid are analyzed. The results indicate that vortex-induced vibration is the most serious when the valve is opened or closed. The variation of the flow velocity and the pressure difference have obvious effects on vortex-induced vibration of the valve. The intensity of the variation affects the main frequency and amplitude of vortex-induced vibration. Using thermal-fluid-solid coupling modal analysis instead of traditional modal analysis, the modal frequency under the working state of the valve is obtained. It is compared with the main frequency of vortex shedding, and vortex-induced resonance does not occur in the multistage pressure reducing valve.

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On Pseudo-state Matrices of Fractional-Order Multi-frequency Oscillators: A Routh Array Based Oscillatory Criterion and Harmonic Preserving Transformations

Tavazoei

2023

Circuits Syst Signal Process

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Eigen and temporal characteristics of multi-frequency parametrically-excited rotor-oscillator systems

Cited by 7 publications

References 32 publications

Stability of general asymmetric-anisotropic rotors subject to harmonic follower force

Stability of general asymmetric-anisotropic rotors subject to harmonic follower force

Evaluation the possibility of vortex-induced resonance for a multistage pressure reducing valve

On Pseudo-state Matrices of Fractional-Order Multi-frequency Oscillators: A Routh Array Based Oscillatory Criterion and Harmonic Preserving Transformations

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