Analysis of Thrust Bearings Operating in Turbulent Regime

1988 ◽  
Vol 110 (3) ◽  
pp. 555-560 ◽  
Author(s):  
M. Harada ◽  
H. Aoki
Keyword(s):  
Steady State ◽  
Thrust Bearing ◽  
Three Dimensional ◽  
Cross Coupling ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Pressure Gradients ◽  
Mixing Length ◽  
Thrust Bearings ◽  
Mixing Length Theory

This paper relates to the turbulent motion in the lubricant fluid film with centrifugal effects and the lubrication theory for thrust bearings operating in turbulent regime. Using Prandtl’s mixing-length theory, three-dimensional turbulent velocity distributions, including pressure gradients and centrifugal effects, are calculated, and the cross-coupling of nonplanar flow of the lubricant fluid film is discussed. From these results, turbulent lubrication equations with centrifugal effects are derived. Applying these lubrication equations to a sectorial inclined thrust bearing, the steady-state characteristics and the dynamic ones are calculated.

Analysis of Bearings Operating in Turbulent Regime

1962 ◽  
Vol 84 (1) ◽  
pp. 139-151 ◽  
Author(s):  
V. N. Constantinescu
Keyword(s):  
Three Dimensional ◽  
Lubricant Layer ◽  
Turbulent Regime ◽  
Mixing Length ◽  
Thrust Bearings ◽  
Mixing Length Theory

Proceeding from the results obtained previously [5] this paper analyzes theoretically the three-dimensional motion in the lubricant layer by using Prandtl’s mixing length theory. Formulas and diagram are presented for calculating journal and thrust bearings subjected to turbulent lubrication.

scholarly journals Run-Up Simulation of a Semi-Floating Ring Supported Turbocharger Rotor Considering Thrust Bearing and Mass-Conserving Cavitation

Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 44
Author(s):  
Christian Ziese ◽  
Cornelius Irmscher ◽  
Steffen Nitzschke ◽  
Christian Daniel ◽  
Elmar Woschke
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Three Dimensional ◽  
Reliable Prediction ◽  
Two Phase ◽  
Hydrodynamic Bearings ◽  
Thrust Bearings ◽  
Run Up ◽  
The Impact

The vibration behaviour of turbocharger rotors is influenced by the acting loads as well as by the type and arrangement of the hydrodynamic bearings and their operating condition. Due to the highly non-linear bearing behaviour, lubricant film-induced excitations can occur, which lead to sub-synchronous rotor vibrations. A significant impact on the oscillation behaviour is attributed to the pressure distribution in the hydrodynamic bearings, which is influenced by the thermo-hydrodynamic conditions and the occurrence of outgassing processes. This contribution investigates the vibration behaviour of a floating ring supported turbocharger rotor. For detailed modelling of the bearings, the Reynolds equation with mass-conserving cavitation, the three-dimensional energy equation and the heat conduction equation are solved. To examine the impact of outgassing processes and thrust bearing on the occurrence of sub-synchronous rotor vibrations separately, a variation of the bearing model is made. This includes run-up simulations considering or neglecting thrust bearings and two-phase flow in the lubrication gap. It is shown that, for a reliable prediction of sub-synchronous vibrations, both the modelling of outgassing processes in hydrodynamic bearings and the consideration of thrust bearing are necessary.

scholarly journals A Unified View of the Law of the Wall Using Mixing-Length Theory

1973 ◽  
Vol 24 (1) ◽  
pp. 55-70 ◽  
Author(s):  
V C Patel
Keyword(s):  
Friction Velocity ◽  
Critical Value ◽  
Wall Region ◽  
Pressure Gradients ◽  
Mixing Length ◽  
Stress Distributions ◽  
General Validity ◽  
Law Of The Wall ◽  
Unified View ◽  
Mixing Length Theory

SummaryIt is shown that, if the well-known mixing-length formula is regarded simply as a relationship between the velocity and the stress distributions in the wall region of a turbulent flow, then a truly universal distribution of mixing length is sufficient to describe the experimentally observed departures of the velocity distribution from the usual law of the wall as a result of severe pressure gradients and transverse surface curvature. Comparisons have been made with a wide variety of experimental data to demonstrate the general validity of the mixing-length model in describing the flow close to a smooth wall.An extension of the re-laminarisation criterion of Patel and Head, and some experimental evidence, suggest that the thick axisymmetric boundary layer on a slender cylinder placed axially in a uniform stream cannot be maintained in a fully turbulent state for values of the Reynolds number, based on friction velocity and cylinder radius, below a certain critical value.

Performance of Elastic, Centrally Pivoted, Sector, Thrust-Bearing Pads—Part I

1961 ◽  
Vol 83 (2) ◽  
pp. 169-178 ◽  
Author(s):  
B. Sternlicht ◽  
J. C. Reid ◽  
E. B. Arwas
Keyword(s):  
Experimental Data ◽  
Approximate Calculation ◽  
Thrust Bearing ◽  
Full Scale ◽  
Fluid Film ◽  
Thermal Gradients ◽  
Thrust Bearings ◽  
Adiabatic Conditions ◽  
Tilting Pad

This is the first of three papers on the results of a recently completed study of the performance of tilting pad thrust bearings. It describes a method of analysis that was worked out for these bearings, which includes viscosity variations in the fluid film and an approximate calculation of the pad deflections caused by the hydrodynamic pressures. Equilibrium of moments is satisfied, laminar and adiabatic conditions are assumed, and the lubricant is incompressible. The two subsequent papers of this series will describe: (a) The results of an analysis which includes a more rigorous determination of pad deflections caused by hydrodynamic pressures and thermal gradients. (b) A comparison of analytical results with experimental data obtained in full-scale bearing tests.

Transient and Steady State Vibration Analysis of a Wavy Thrust Bearing

2005 ◽  
Vol 128 (1) ◽  
pp. 139-145 ◽  
Author(s):  
H. Zhao ◽  
F. K. Choy ◽  
M. J. Braun
Keyword(s):  
Steady State ◽  
Vibration Analysis ◽  
Thrust Bearing ◽  
Numerical Procedure ◽  
Operating Conditions ◽  
System Stability ◽  
Thrust Bearings ◽  
External Perturbations ◽  
Vibration Signature ◽  
Transient And Steady State

This paper describes a numerical procedure for analyzing the dynamics of transient and steady state vibrations in a wavy thrust bearing. The major effects of the wavy geometry and the operating parameters on the dynamic characteristics of the bearing had been discussed in a previous paper; the present paper thus concentrates on examining the relationships between the development of the transient and steady state vibrations when operating conditions are parametrically varied. Special attention is given to the development of steady state vibrations from initial transients with comparisons and consequences to the overall system stability. Numerical based vibration signature analysis procedures are then used to identify and quantify the transient vibrations. The conclusions provide general indicators for designing wavy thrust bearings that are less susceptible to transients induced by external perturbations.

Sensitivity Studies for the Shallow-Pocket Geometry of a Hydrostatic Thrust Bearing

2003 ◽  
Author(s):  
Robert E. Johnson ◽  
Noah D. Manring
Keyword(s):  
Closed Form ◽  
Thrust Bearing ◽  
Three Dimensional ◽  
Closed Form Expression ◽  
Pocket Depth ◽  
Thrust Bearings ◽  
Heavy Equipment ◽  
Load Carrying ◽  
Sensitivity Studies ◽  
Basic Features

Hydrostatic thrust bearings have been the object of considerable research for many years. The attention that these bearings have received is primarily due to the important role they play in the design and operation of heavy equipment. In this role, the hydrostatic thrust bearing is often considered to be the “Achilles heel” of the total machine system as failures result in catastrophic difficulties and expensive repairs. The objectives of this research are to examine the nuances of designing a hydorstatic thrust bearing using a shallow pocket as opposed to the more traditional deep pocket design. By using a two-dimensional model for this geometry, the basic features of the shallow pocket design are extracted in closed-form and behaviors that would be expected in the three-dimensional setting are identified. In this research, a single dimensionless parameter is used to describe the influence of the bearing speed under laminar flow conditions. The principal results of this research are closed-form expression that describe the load carrying capcity of the bearing, the tilting moment exerted on the bearing by a skewed pressure distribution, and the volumetric leakage of the bearing. Sensitivity studies are conducted using these results and the influence of small perturbations of the pocket depth are identified for bearings with different pocket widths. These results are discussed and conclusions are itemized in the final section of the paper.

Solution for the Pressure and Temperature in Thrust Bearings Operating in the Thermohydrodynamic Turbulent Regime

1974 ◽  
Vol 96 (1) ◽  
pp. 58-68 ◽  
Author(s):  
K. H. Huebner
Keyword(s):  
Thermal Effects ◽  
Eddy Viscosity ◽  
Turbulent Transport ◽  
Three Dimensional ◽  
Turbulent Shear ◽  
Turbulent Regime ◽  
Reynolds Analogy ◽  
Thrust Bearings ◽  
Law Of The Wall ◽  
Lubricant Viscosity

A numerical solution is developed for the equations governing the turbulent thermohydrodynamic flow in a sector shaped thrust bearing. The lubricant viscosity is taken as a function of the three-dimensional temperature distribution in the fluid-film. Three-dimensional heat transfer between the lubricant and both the moving and stationary solids is included in the analysis. Isotropy of the turbulent mixing process is assumed. The “law of the wall” for turbulent shear flows is used to define an eddy viscosity based on the local wall shear stress and the viscosity within the film. A modified Reynolds analogy is assumed to relate the turbulent transport of heat and momentum. According to the Ng-Pan theory the momentum transport equations are linearized by assuming the nonplanar flow is a small perturbation of turbulent Couette flow. Thermal effects are shown to be less pronounced in turbulent flow than in laminar flow.

A Length-Scale Model For Developing Turbulent Flow in a Rectangular Duct

1977 ◽  
Vol 99 (2) ◽  
pp. 347-356 ◽  
Author(s):  
F. B. Gessner ◽  
A. F. Emery
Keyword(s):  
Reynolds Stress ◽  
Three Dimensional ◽  
Scale Model ◽  
Length Scale ◽  
Pressure Gradients ◽  
Mixing Length ◽  
Two Dimensional ◽  
Rectangular Duct ◽  
Corner Flows ◽  
Theory And Experiment

A three-dimensional mixing length model is proposed for modeling local Reynolds stress behavior in rectangular ducts of arbitrary aspect ratio. The model is applicable to both developing and fully-developed flows, and can be applied to other 90-degree corner flows with mild streamwise pressure gradients. Comparisons between theory and experiment show that all components of the Reynolds stress tensor are modeled reasonably well, both in the vicinity of a corner and in two-dimensional regions away from the corner.

scholarly journals On the Possibilities of Decreasing Power Loss in Large Tilting Pad Thrust Bearings

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Michal Wasilczuk ◽  
Grzegorz Rotta
Keyword(s):  
Power Loss ◽  
Power Plants ◽  
Thrust Bearing ◽  
Fluid Film ◽  
Total Power ◽  
Thrust Bearings ◽  
Oil Supply ◽  
Water Power ◽  
Lubricant Flow ◽  
Tilting Pad

Different systems of direct oil supply have been developed in order to facilitate efficient introduction of fresh lubricant to the oil gap and reduction of churning power loss in tilting pad thrust bearings. Up to now there is no documented application of the supply groove in large thrust bearings used in water power plants. The results of modeling lubricant flow in the lubricating groove of a thrust bearing pad will be presented in the paper. CFD software was used to carry out fluid film calculations. Such analysis makes it possible to modify groove geometry and other parameters and to study their influence on bearing performance. According to the results a remarkable decrease in total power loss due to avoiding churning losses can be observed in the bearing.

A Study of Fluid Velocities in Tribological Fluid Film

1994 ◽  
Vol 116 (1) ◽  
pp. 133-138 ◽  
Author(s):  
A. K. Tieu ◽  
P. B. Kosasih ◽  
M. R. Mackenzie
Keyword(s):  
Reynolds Number ◽  
Poiseuille Flow ◽  
Velocity Profiles ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Mixing Length ◽  
Fluid Film Bearings ◽  
Fluid Velocities ◽  
Planar Flows ◽  
Narrow Gaps

Recently a model of Reynolds stress in turbulent lubrication theory was proposed by Tieu and Kosasih (1992) based on a modified Van Driest mixing length formula. It was developed from a study of Poiseuille flow velocities in narrow gaps. As a continuation of that study, this paper describes an investigation into fluid velocities in fluid film bearings. Experimental velocity profiles of planar flows in various film geometries are compared with the profiles calculated using the mixing length model in the transition-turbulent regime. Excellent agreements have been attained, confirming the validity of the formula in the superlaminar theory. The effects of Reynolds number and pressure gradient on nonplanar velocity profiles are also presented.

Sign in / Sign up

Export Citation Format

Share Document