Global dynamics of a flexible asymmetrical rotor

Yu, Tian-Jun; Sha, Zhihua; Yang, Xiao‐Dong; Zhang, Wei

doi:10.1007/s11071-017-3927-x

“…However, current research generally assumes that the outer pipe (typically considered as the wellbore) is fixed [16,17]. Although there are studies considering an elastic-supported rotor-stator system with flexible outer pipes [18][19][20][21], most of these studies assume that the stiffness of the stator's elastic support is substantial.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear coupled motions of a pipe-in-pipe system experiencing vortex-induced vibrations

Hou,

Long,

Meng

et al. 2024

Nonlinear Dyn

1

0

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This paper delves into the dynamics of the pipe-in-pipe system, crucial in offshore oil and gas exploration, featuring an inner drill string nestled within an outer riser. A reduced-order model with five degrees of freedom is proposed to capture the coupled dynamics of this system. Here, the inner drill string is depicted as a torsional-lateral coupled rotor constrained by the outer riser. In contrast, the outer riser is modeled as a suspended stator subjected to vortex-induced excitations and contact forces. The model incorporates nonlinearities, including dry frictions, collisions, loss of contact, and nonlinear damping through the van der Pol wake oscillator. This comprehensive model allows an indepth exploration of the dynamics of the coupled pipein-pipe system. Parametric analysis is conducted based on the non-dimensional numerical model, revealing a novel and stable whirling phenomenon termed "follower whirling" at low rotary speeds of the drill string. During this stable follower whirling, the riser's vortex-induced vibration traces an "8"-shaped trajectory, while the

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“…However, current research generally assumes that the outer pipe (typically considered as the wellbore) is fixed [16,17]. Although there are studies considering an elastic-supported rotor-stator system with flexible outer pipes [18][19][20][21], most of these studies assume that the stiffness of the stator's elastic support is substantial.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Coupled Motions of a Pipe-in-Pipe System Experiencing Vortex-Induced Vibrations

Hou,

Liu,

Long

et al. 2023

Preprint

0

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This paper delves into the dynamics of the pipe-in-pipe system, crucial in offshore oil and gas exploration, featuring an inner drill string nestled within an outer riser. A reduced-order model with five degrees of freedom is proposed to capture the coupled dynamics of this system. Here, the inner drill string is depicted as a torsional-lateral coupled rotor constrained by the outer riser. In contrast, the outer riser is modeled as a suspended stator subjected to vortex-induced excitations and contact forces. The model incorporates nonlinearities, including dry frictions, collisions, loss of contact, and nonlinear damping through the van der Pol wake oscillator. This comprehensive model allows an in-depth exploration of the dynamics of the coupled pipe-in-pipe system. Parametric analysis is conducted based on the non-dimensional numerical model, revealing a novel and stable whirling phenomenon termed "follower whirling" at low rotary speeds of the drill string. During this stable follower whirling, the riser's vortex-induced vibration traces an "8"-shaped trajectory, while the drill string follows suit, oscillating between forward- and backward-whirling, forming a "C"-shaped trajectory relative to the riser. Additionally, within the frequency lock-in region of the vortex-induced vibration, frequency analysis indicates induced nonlinear resonances through the continuous contact whirling of the drill string, showcasing a strong coupling between the drill string and the riser. In contrast, within the non-lock-in region, the system dynamics are primarily dominated by the backward whirling of the drill string. Furthermore, the parametric study reveals that the backward whirling of the drill string can significantly reduce both the cross-flow and the in-line vortex-induced vibration of the riser. However, as a side-effect, it introduces higher-frequency vibrations and potential fatigue damage to the inner drill string. This research lays a foundation for comprehending the coupled dynamics of pipe-in-pipe systems in offshore drilling applications.

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“…Yagasaki [23] & Zhang et al [24] utilized the Melnikov method, and the research show that abundant bifurcation behavior and chaos motions occur in vibrations of the microcantilever. Yu et al [25,26] investigated nonlinear dynamics of a flexible rotor system, and obtained the parameter range of the occurrence of chaos motion in the sense of Smale horseshoes. Siewe et al [27,28] [31], and Li et al [32] gave the critical parameter curve of the Duffing oscillator for the existence of chaos in the Smale horse sense by Melnikov method.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Dynamic Analysis and Chaos Prediction of Grinding Motorized Spindle System

Jia

¹

,

Gao

²

,

Li

³

et al. 2019

Shock and Vibration

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The paper determines the impact factors of dynamics of a motorized spindle rotor system due to high speed: centrifugal force and bearing stiffness softening. A nonlinear dynamic model of the grinding motorized spindle system considering the above impact factors is constructed. Through system simulation including phase portraits and Poincaré map, the periodic behavior and chaotic behavior of the nonlinear grinding motorized spindle system are revealed. The threshold curve of chaos motion is obtained through the Melnikov method. The conclusion can provide a theoretical basis for researching deeply the dynamic behaviors of the grinding motorized spindle system.

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Global dynamics of a flexible asymmetrical rotor

Cited by 16 publications

References 54 publications

Nonlinear coupled motions of a pipe-in-pipe system experiencing vortex-induced vibrations

Nonlinear coupled motions of a pipe-in-pipe system experiencing vortex-induced vibrations

Nonlinear Coupled Motions of a Pipe-in-Pipe System Experiencing Vortex-Induced Vibrations

Nonlinear Dynamic Analysis and Chaos Prediction of Grinding Motorized Spindle System

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