A Linearized Turbulent Lubrication Theory

Ng, Chung-Wah; Pan, C. H. T.

doi:10.1115/1.3650640

Cited by 286 publications

(145 citation statements)

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“…Theoretical models developed to include turbulence in fluid film lubrication use either mixing length or the law of wall and eddy diffusivity concepts. Most widely used theories of turbulent lubrication are those of Ng and Pan 1) and Elrod and Ng 2) which are based on law of wall and the eddy diffusivity concept and bulk flow theory of Hirs 3) . It is known that these theories lead to almost identical results at high Reynolds numbers.…”

Section: Introductionmentioning

confidence: 99%

Dynamic and Static Characteristics of Wavy Annular Seals in Turbulent Flow

Gautam

Ghosh

2010

Tribology Online

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This paper presents results of a theoretical analysis to determine the leakage flow and dynamic characteristics of circumferential wave geometry annular seals using turbulent lubrication theory. Turbulent lubrication equations based on an eddy viscosity model have been used to develop the turbulent Reynolds equation. Convective fluid inertia effects have been incorporated using the perturbation approach in turbulent lubrication. To determine the dynamic characteristics i.e. stiffness, damping and whirl ratio, perturbation theory for small amplitude vibration of the journal center has been adopted. In general, it has been found that circumferential wave geometry improves the performance of the annular seal at higher speeds and increases in the L/D and taper ratios.

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Section: Introductionmentioning

confidence: 99%

Dynamic and Static Characteristics of Wavy Annular Seals in Turbulent Flow

Gautam

Ghosh

2010

Tribology Online

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“…Compared with the laminar simulation results and experimental data, turbulence simulation results confirm that turbulence effect should be considered for bearing lubricant flows [17,18]. Ng and Pan [19] further investigated the theories based on law of wall and mixing length theory. Considering the verified theoretical results based on law of wall, Hirs [20] proposed a bulk-flow theory for bearing lubricant simulation.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Turbulence Models for a Superlaminar Journal Bearing

Ding

Ren

et al. 2018

Advances in Tribology

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With rotating machineries working at high speeds, oil flow in bearings becomes superlaminar. Under superlaminar conditions, flow exhibits between laminar and fully developed turbulence. In this study, superlaminar oil flow in an oil-lubricated tilting-pad journal bearing is analyzed through computational fluid dynamics (CFD). A three-dimensional bearing model is established. CFD results from the laminar model and 14 turbulence models are compared with experimental findings. The laminar simulation results of padside pressure are inconsistent with the experimental data. Thus, the turbulence effects on superlaminar flow should be considered. The simulated temperature and pressure distributions from the classical fully developed turbulence models cannot correctly fit the experimental data. As such, turbulence models should be corrected for superlaminar flow. However, several corrections, such as transition correction, are unsuitable. Among all the flow models, the SST model with low-Re correction exhibits the best pressure distribution and turbulence viscosity ratio. Velocity profile analysis confirms that a buffer layer plays an important role in the superlaminar boundary layer. Classical fully developed turbulence models cannot accurately predict the buffer layer, but this problem can be resolved by initiating an appropriate low-Re correction. Therefore, the SST model with low-Re correction yields suitable results for superlaminar flows in bearings.

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“…The relative pocket clearance C c is then found by means of Eq. (13). It is usually in the range from 0.8/1000 to 2.2/1000.…”

Section: Journal Of Advanced Mechanical Design Systems and Manufactmentioning

confidence: 99%

“…The turbulence phenomena are treated with the classic linearized Ng-Pan model (13) and the functions K ϑ ,, K z in Eq. (22) are computed in accordance with (14) .…”

Section: Journal Of Advanced Mechanical Design Systems and Manufactmentioning

confidence: 99%

Computer-Aided Design of Pocket Elliptical Journal Bearings, Part 1: Theory

Stefani

2013

JAMDSM

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A computer-aided design procedure suitable for pocket elliptical journal bearings for turbomachineries is proposed. After the description of their geometry and manufacturing, the driving geometric parameters characteristic of the pocket bearing are identified together with the design variants that influence their choice, like supply groove layout and the axial size of the pocket. The concept of journal mobility plot, capable to ease the post-processing of results and useful in journal vibration monitoring, is adapted to pocket elliptical bearings and, in general, to non-circular bearings. The proposed design evaluation includes a calculation sequence involving geometric parameters, FEM simulation and the calculation of proper performance indicators, from which the global performance of the bearing is finally computed.

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A Linearized Turbulent Lubrication Theory

Cited by 286 publications

References 0 publications

Dynamic and Static Characteristics of Wavy Annular Seals in Turbulent Flow

Dynamic and Static Characteristics of Wavy Annular Seals in Turbulent Flow

Numerical Investigation of Turbulence Models for a Superlaminar Journal Bearing

Computer-Aided Design of Pocket Elliptical Journal Bearings, Part 1: Theory

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