Frequency-swept rotating input perturbation techniques and identification of the fluid force models in rotor/bearing/seal systems and fluid handling machines

Muszynska, A.; Bently, Donald E.

doi:10.1016/0022-460x(90)90571-g

Cited by 85 publications

(73 citation statements)

References 6 publications

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“…In order to simulate the nonlinearity of the sliding bearing, some nonlinear oil film force models have been proposed, such as Capone G [1,2]. The Muszynska model [3][4][5] was introduced as a simple model of nonlinear fluid dynamic forces generated in bearings as well as in seals based on the results of a series of experiments. A parameter called the fluid average circumferential velocity ratio is used to describe the characteristic of the fluid motion as a whole.…”

Section: Introductionmentioning

confidence: 99%

Response Characteristics of Looseness‐Rubbing Coupling Fault in Rotor‐Sliding Bearing System

Liu

Xue

Jia

et al. 2017

Mathematical Problems in Engineering

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For the diagnosis of looseness-rubbing coupling fault of rotor-sliding bearing system caused by bolt looseness fault, the mechanical model and finite element model of dual-disc rotor system with looseness-rubbing coupling fault are established based on the nonlinear finite element method, nonlinear oil film force, looseness stiffness model, and Hertz contact theory. With the augmented Lagrange method, contact constraint conditions are dealt with to ensure that the rotary disk and casing contact with each other meeting boundary penetrating depth within the prescribed tolerance range. And then the dynamics characteristics of the health rotor system supported by sliding bearing are studied. Combined with experimental study and simulation analysis, it is found that the looseness-rubbing coupling fault is often characterized by rubbing fault, the lower part of the time-domain fluctuated shape is denser, while the upper part is relatively loose, and multiple nested half ellipse is shown in orbit diagram. Because of the loosing stiffness and rubbing force, the phenomenon of unstable oil film is depressed. The appearance of the first-and second-order oil film oscillation phenomenon is delayed. It could be used as a theoretical basis for diagnosing looseness-rubbing coupling fault of rotor-sliding bearing system.

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Section: Introductionmentioning

confidence: 99%

Response Characteristics of Looseness‐Rubbing Coupling Fault in Rotor‐Sliding Bearing System

Liu

Xue

Jia

et al. 2017

Mathematical Problems in Engineering

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“…In general, the harmonic order of oilwhirl subsynchronous vibrations is close to 0.5 × revolution (0.5X) [7][8][9]. However, when the shaft rotational speed is twice higher than the first flexural critical speed of the rotor, the frequency of the dominant subharmonic component of the shaft vibrations can be synchronised with that of the first flexural critical speed [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Effects of the Hot Alignment of a Power Unit on Oil-Whip Instability Phenomena

Vania

Pennacchi

2010

International Journal of Rotating Machinery

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This paper shows the results of the analysis of the dynamic behaviour of a power unit, whose shaft-train alignment was significantly influenced by the machine thermal state, that was affected in operating condition by high subsynchronous vibrations caused by oil-whip instability phenomena. The dynamic stiffness coefficients of the oil-film journal bearings of the generator were evaluated considering the critical average journal positions that caused the instability onsets. By including these bearing coefficients in a mathematical model of the fully assembled machine, the real part of the eigenvalue associated with the first balance resonance of the generator rotor became positive. This paper shows the successful results obtained by combining diagnostic techniques based on mathematical models of journal bearings and shaft train with detailed analyses of monitoring data aimed to investigate the effects of the hot alignment of rotating machines on the occurrence of oil-whip instability onsets.

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“…The Muszynska's model is applied to investigate the nonlinear behaviors of seal fluid force, which can be expressed as [12]:…”

Section: Nonlinear Seal Fluid Force (Airflow Excited Force)mentioning

confidence: 99%

Dynamic Analysis on Nonlinear Fluid-Structure Interaction Forces of Rub-Impact Rotor System

Luo¹,

Zhang²,

Wu³

et al. 2014

TOMEJ

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Abstract:Based on the coupling model of nonlinear oil-film force and nonlinear seal fluid force, a nonlinear dynamic model of rotor system with rub-impact fault is set up. The dynamic characteristics of the system were studied with numerical simulation and the effects of airflow excited force, rubbing gap and stiffness parameters on movement characteristics of the rotor were analyzed. The results indicate that the airflow excited force can significantly restrain the stability and amplitude of rubbing rotor. The less rubbing gap and larger rubbing stiffness are in favor of the stability of the system.

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Frequency-swept rotating input perturbation techniques and identification of the fluid force models in rotor/bearing/seal systems and fluid handling machines

Cited by 85 publications

References 6 publications

Response Characteristics of Looseness‐Rubbing Coupling Fault in Rotor‐Sliding Bearing System

Response Characteristics of Looseness‐Rubbing Coupling Fault in Rotor‐Sliding Bearing System

Effects of the Hot Alignment of a Power Unit on Oil-Whip Instability Phenomena

Dynamic Analysis on Nonlinear Fluid-Structure Interaction Forces of Rub-Impact Rotor System

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