Stability and bifurcation phenomena of Laval/Jeffcott rotors in semi-floating ring bearings

Boyaci, Aydin; Lu, Daixing; Schweizer, Bernhard

doi:10.1007/s11071-014-1759-5

Cited by 40 publications

(9 citation statements)

References 17 publications

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“…Identical single hydrodynamic journal bearings on the left and right end support the assembly. A point mass p is fixed to the disk at a given radial distance p from the center of the shaft to account for the centrifugal imbalance force (Ω S ) = P P (2 Ω S ( )) 2 , where Ω S is the shaft's rotational speed and is the time variable. To simulate a smooth run-up Ω S ( ) = const.…”

Section: Customized Laval/jeffcott-rotor In Plain Hydrodynamic Bearingsmentioning

confidence: 99%

“…Further details on the implemented bearing formulation are given in Section 2.4. Imbalances can be modeled either by point masses connected to a local position on beam or disk elements, or by centrifugal forces P, P, (2πΩ S ) 2 , where P, denotes the k-th imbalance mass, P, the respective radial distance, and Ω the rotor's angular frequency. The rotordynamic model employed in the present work relies on rotor beam elements based on a linear beam formulation, including the Rayleigh model to represent material damping [13], which are used to discretize the turbocharger's shaft along its rotor axis combined with rigid disk elements which correctly represent gyroscopic effects (e.g., of the turbine or compressor wheel).…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures

Bernhauser¹,

Heinisch²,

Schörgenhumer

et al. 2017

Lubricants

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Increasing quality demands of combustion engines require, amongst others, improvements of the engine's acoustics and all (sub)components mounted to the latter. A significant impact to the audible tonal noise spectrum results from the vibratory motions of fast-rotating turbocharger rotor systems in multiple hydrodynamic bearings such as floating bearing rings. Particularly, the study of self-excited non-linear vibrations of the rotor-bearing systems is crucial for the understanding, prevention or reduction of the noise and, consequently, for a sustainable engine acoustics development. This work presents an efficient modeling approach for the investigation, optimization, and design improvement of complex turbocharger rotors in hydrodynamic journal bearings, including floating bearing rings with circular and non-circular bearing geometries. The capability of tonal non-synchronous vibration prevention using non-circular bearing shapes is demonstrated with dynamic run-up simulations of the presented model. These findings and the performance of our model are compared and validated with results of a classical Laval/Jeffcott rotor-bearing model and a specific turbocharger model found in the literature. It is shown that the presented simulation method yields fast and accurate results and furthermore, that non-circular bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise.

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Section: Customized Laval/jeffcott-rotor In Plain Hydrodynamic Bearingsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures

Bernhauser¹,

Heinisch²,

Schörgenhumer

et al. 2017

Lubricants

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“…Based on the 2π -film and π-film assumption, San Andres and Vance (1988) proposed an analytical oil force formula for the SFD to investigate the dynamic response of the rotor, which indicated that the probability of a bi-stable response decreased moderately with increasing fluid inertia. The instability phenomenon caused by self-excited vibrations in a fully-floating ring-bearingrotor system was investigated by Schweizer (Boyaci et al, 2015). Based on the assumption of short bearings, Zhou et al (2014) analyzed the dynamic characteristics of a floating ring SFD-bearing-rotor system.…”

Section: Introductionmentioning

confidence: 99%

Dynamic analysis of an elastic ring squeeze film damper supported rotor using a semi-analytic method

Han

Zhisai

Zhang

et al. 2020

Engineering Applications of Computational Fluid Mechanics

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To speed up the calculation of dynamic analysis for elastic ring squeeze film dampers (ERSFDs) and investigate the dynamic characteristics of ERSFD-rotor systems, a semi-analytic method (SAM) is proposed for analyzing oil film pressure and force. This method is subsequently verified by comparison with numerical simulation and experimental results. Based on this SAM, an improved dynamic model of an ERSFD-supported rotor is developed by coupling the kinetic equations of the rotor with the determination of elastic deformation. Using this method, the oil coefficients and vibration behaviors of the rotor such as the amplitude-frequency relation and the influence of sudden excitation are investigated. The results reveal that the equivalent oil coefficients and damping ratio of the system can be increased significantly by the adoption of ERSFDs. Therefore, the nonlinear bistable response occasionally occurring in traditional squeeze film damper (SFD) supported rotors is effectively suppressed and the transient vibration process caused by sudden unbalanced excitation action is significantly shortened. The SAM enables one to reduce the computation time of the previous method by more than 90%. Such a reduction greatly improves the computational efficiency.

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“…The possibilities of incorporating floating ring bearing simulation into rotor dynamic algorithms are many and are extensively discussed in the literature. The numerical solution of the Reynolds equation for both inner and outer oil films has been performed with numerical methods such as FDM, FEM, and CFD [7][8][9][10][11][12][13]. Such methods are quite accurate but, even after the development of very efficient solvers, they are considered slower in comparison to direct formulas for the bearing's impedance forces yielded from short/long bearing approximation.…”

Section: Introductionmentioning

confidence: 99%

“…This paper does not aim to delve into the mechanisms of instabilities in turbosystems; this issue has been thoroughly discussed in recent [1][2][3][4][5][6][11][12][13][14] and past literature [7][8][9][10]. It aims to use two theoretical models for floating ring bearing simulation that are based on a recent achievement of analytical solution of the Reynolds equation in finite-length journal bearings [23][24][25] and in the application on the floating ring bearings of finite length [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

An Investigation on the Dynamics of High-Speed Systems Using Nonlinear Analytical Floating Ring Bearing Models

Chasalevris¹

2016

International Journal of Rotating Machinery

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The scope of this paper is to investigate the dynamics of a rotor-bearing system of high-speed under recently developed analytical bearing models. The development of a theory that can yield the dynamic response of a high-speed system without short/long bearing approximation and without time-consuming numerical methods for the finite-length bearing model is the outcome of this work. The rotor system is introduced as a rigid body so that the dynamics of the system are influenced only from the nonlinear bearing forces which are introduced with closed form expressions. The outcome is a system of nonlinear equations and its solution produces the dynamic response of the high-speed system using exact analytical solution for the bearing forces. The transient dynamic response of the system is evaluated through the wide range of rotating speed and under different bearing solutions including short bearing approximation, presenting the subsynchronous components that are developed when instabilities occur. Time-frequency analysis of the resulting response time-series is presented and the outcome is compared with that obtained from numerical solution of the bearing lubrication and with the short bearing approximation model.

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Stability and bifurcation phenomena of Laval/Jeffcott rotors in semi-floating ring bearings

Cited by 40 publications

References 17 publications

The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures

The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures

Dynamic analysis of an elastic ring squeeze film damper supported rotor using a semi-analytic method

An Investigation on the Dynamics of High-Speed Systems Using Nonlinear Analytical Floating Ring Bearing Models

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