Analysis of Thermal Effects in Hydrodynamic Bearings

1986 ◽  
Vol 108 (2) ◽  
pp. 219-224 ◽  
Author(s):  
R. Boncompain ◽  
M. Fillon ◽  
J. Frene
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Effects ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Heat Transfer Equation ◽  
Reversed Flow ◽  
Theoretical Results ◽  
Generalized Reynolds Equation ◽  
Good Agreement

A general THD theory and a comparison between theoretical and experimental results are presented. The generalized Reynolds equation, the energy equation in the film, and the heat transfer equation in the bush and the shaft are solved simultaneously. The cavitation in the film, the lubricant recirculation, and the reversed flow at the inlet are taken into account. In addition, the thermoelastic deformations are also calculated in order to define the film thickness. Good agreement is found between experimental data and theoretical results which include thermoelastic displacements of both the shaft and the bush.

Forced Cooling of a Slider Bearing With Wedge Film

1968 ◽  
Vol 90 (1) ◽  
pp. 297-304 ◽  
Author(s):  
H. Tahara
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Flow ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Heat Flow Rate ◽  
Slider Bearing ◽  
The Mean ◽  
Forced Cooling ◽  
Generalized Reynolds Equation

This paper deals with the forced cooling problem of a slider bearing with wedge film of finite length, where most of the heat generated in the lubricant film is removed by a coolant which flows under the surface of the bearing pad. Analysis was made on the generalized Reynolds’ equation, including viscosity variations with temperature throughout the film and the energy equation. Simultaneous solutions of these equations seemed to be supported by experiments. From the analysis, calculations were made on the heat flow rate into the coolant, the temperature difference between slider and pad surfaces, bearing characteristics using the representative viscosity, and the mean heat transfer coefficient of the wedge film.

Thermal-EHD contacts lubricated with oil/refrigerant solutions: a new cavitation modeling approach based on refrigerant solubility

2022 ◽  
pp. 1-19
Author(s):  
Fan Zhang ◽  
Nicolas Fillot ◽  
Rudolf Hauleitner ◽  
Guillermo Morales Espejel
Keyword(s):  
Thermal Effects ◽  
Reynolds Equation ◽  
Conservation Equation ◽  
Point Contacts ◽  
Energy Conservation Equation ◽  
Cavitation Region ◽  
Cavitation Intensity ◽  
Thickness Prediction ◽  
Generalized Reynolds Equation ◽  
Good Agreement

Abstract A first cavitation modeling with thermal effects for oil/refrigerant solutions lubricated ElastoHydroDynamic (EHD) point contacts is reported in this work. The solubility of the oil/refrigerant system is introduced into the Generalized Reynolds equation coupled with the elasticity equation and the energy conservation equation. The numerical results show a very good agreement with the published experimental results concerning film thickness prediction. Moreover, the present model describes the cavitation region on a physical basis. A discussion with other cavitation models from the literature is proposed. It puts into light the necessity of taking into account the solubility of the refrigerant into oil for such problems. Compared to pure oil, oil/refrigerant solutions can potentially reduce the amount of liquid oil for the next contact due to its higher cavitation intensity.

A Simplified One-Dimensional Thermal Model for Journal Bearings

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Daquan Liu ◽  
Wen Zhang ◽  
Tiesheng Zheng
Keyword(s):  
Thermal Effects ◽  
Thermal Model ◽  
Reynolds Equation ◽  
Computing Time ◽  
One Dimensional ◽  
Lubricating Film ◽  
Direct Solution Method ◽  
The One ◽  
Generalized Reynolds Equation ◽  
Good Agreement

The variational approach, which is used to solve the Reynolds equation based on the assumption of constant temperature, is extended to the generalized Reynolds equation calculation. The direct solution method of the generalized Reynolds equation is presented, where the pressure of the nodal points and the cavitation zone boundary of the film can be determined without iterating. A simplified one-dimensional thermal model is built on the basis of the original two-dimensional thermal model. The model not only concerns the thermal effects of the lubricating film, but also offers a direct and rapid numerical algorithm for solving lubricating film temperature field. The numerical results of the temperature distributions for the one model are in good agreement with experiment, and less computing time is needed.

Thermoelastohydrodynamic behavior of misaligned plain journal bearings

2013 ◽  
Vol 227 (11) ◽  
pp. 2582-2599 ◽  
Author(s):  
ZS Zhang ◽  
XD Dai ◽  
YB Xie
Keyword(s):  
Thermal Effects ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Misalignment Angle ◽  
Synthetic Solution ◽  
Simulation Results ◽  
Generalized Reynolds Equation

Under severe operating conditions, the thermal effects and various deformations play an important role in determining the performance of misaligned plain journal bearings. However, the thermal effects and various deformations are rarely considered simultaneously in most studies on the misaligned plain journal bearings. In this article, a comprehensive thermoelastohydrodynamic model of the misaligned plain journal bearings is developed that involves the synthetic solution of the generalized Reynolds equation, three-dimensional energy equation, and heat conduction equations of the solids. Based on this model, series of simulation results are provided to examine the influence of the thermal effects and deformations on the behavior of the misaligned plain journal bearings. In addition, the comparisons between the thermohydrodynamic and complete thermoelastohydrodynamic model are also presented for different misalignment angle and magnitude. Results show that the thermal effects and various deformations should not be ignored because of their significant influence on the film thickness, film pressure as well as other bearings characteristics.

Hydrodynamic Thrust Bearings: Theory and Experiment

1991 ◽  
Vol 113 (3) ◽  
pp. 633-638 ◽  
Author(s):  
A. K. Tieu
Keyword(s):  
Thermal Effects ◽  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Experimental Studies ◽  
Test Rig ◽  
Oil Viscosity ◽  
Thrust Bearings ◽  
Generalized Reynolds Equation

In this paper results from experimental studies and computer simulation of hydro-dynamic tilting thrust bearings are presented. The bearing performance in terms of outlet film thickness, friction coefficient, and bearing temperature was measured in a high speed thrust bearing test rig. The numerical simulation involves the solution of the generalized Reynolds equation and the energy equation, which considers thermal effects on the oil viscosity and the squeezing of the oil film.

Reference Temperatures for Supercritical Laminar Free Convection on a Vertical Flat Plate

1981 ◽  
Vol 103 (4) ◽  
pp. 613-616 ◽  
Author(s):  
A. J. Ghajar ◽  
J. D. Parker
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Free Convection ◽  
Flat Plate ◽  
Reference Temperature ◽  
Variable Property ◽  
Temperature Method ◽  
Theoretical Results ◽  
Vertical Flat Plate ◽  
Good Agreement

A reference temperature method was developed by which heat transfer to fluids in the supercritical region under variable property conditions in laminar free convection on a vertical flat plate can be readily evaluated. Based on this method three generalized plots for Refrigerant-114, water, and carbon dioxide were developed. The results obtained with the reference temperature scheme showed good agreement with the existing experimental data and theoretical results for these three variable property fluids.

Effects of Two Film Rupture Models on the Thermal Analysis of a Journal Bearing

1990 ◽  
Vol 112 (2) ◽  
pp. 183-188 ◽  
Author(s):  
J. D. Knight ◽  
A. J. Niewiarowski
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Journal Bearing ◽  
Effective Length ◽  
Film Rupture ◽  
First Order ◽  
Total Temperature ◽  
Good Agreement

A model for the thermal behavior of lubricant in the cavitated regions of a journal bearing is presented. The model assumes a bubbly mixture of liquid and air and includes the calculation of local mixture properties for the fluid film. Temperature in the film is calculated by a first order approximate energy equation that includes heat transfer between the film and its boundaries. A second order profile is assumed to represent the temperature distribution across the film. The classical Reynolds equation is applied, using a viscosity that does not vary across the film. Results of calculations are compared with published experimental results and with a prior theory that uses an effective length calculation in the cavitation zone. Results are found to be in good agreement with experiment at two different speeds, predicting the peak temperature of the bearing wall within 10 to 20 percent of the total temperature rise. The model predicts the temperature in the cavitated zone with much greater accuracy than the effective length model, with all theoretical values within 2 C of the measured values.

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

An Assessment of the Value of Theory in Predicting Gas-Bearing Performance

1961 ◽  
Vol 83 (2) ◽  
pp. 195-200 ◽  
Author(s):  
S. Cooper
Keyword(s):  
Steady State ◽  
Slip Velocity ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Experimental Methods ◽  
Experimental Results ◽  
Theoretical Investigations ◽  
Gas Bearing ◽  
Theoretical Results

The object of the paper is to indicate the value of theoretical investigations of hydrodynamic finite bearings under steady-state conditions. Methods of solution of Reynolds equation by both desk and digital computing, and methods of stabilizing the processes of solution, are described. The nondimensional data available from the solutions are stated. The outcome of an attempted solution of the energy equation is discussed. A comparison between some theoretical and experimental results is shown. Experimental methods employed and some difficulties encountered are discussed. Some theoretical results are given to indicate the effects of the inclusion of slip velocity, stabilizing slots, and a simple case of whirl.

Numerical Prediction of Combustor Heatshield Flow and Heat Transfer With Sub-Grid-Scale Modelling of Pedestals

2001 ◽  
Author(s):  
John K. Luff ◽  
James J. McGuirk
Keyword(s):  
Heat Transfer ◽  
Life Prediction ◽  
Conjugate Heat Transfer ◽  
Energy Equation ◽  
Flow And Heat Transfer ◽  
Extra Energy ◽  
Scale Modelling ◽  
Heat Transfer Calculation ◽  
Proper Account ◽  
Good Agreement

A goal for computational analysis of combustors is to produce a tool for life prediction. An important part of this will be the prediction of the temperature field in the combustor walls. The complex geometries of combustor components make this a formidable task. In this paper a 3D coupled numerical flow/conjugate heat transfer calculation procedure is presented for a combustor heatshield. Proper account must be taken of the blockage and heat transfer effects of pedestals. A scheme has been developed to account for these effects without resolving the pedestals in the computational grid. Extra sink terms are included in the momentum equations to account for pedestal pressure drop. An extra energy equation is solved to determine the local pedestal temperature and to account for heat transfer between pedestals and fluid. This treatment has been validated against empirical data for arrays of pedestals in ducts with good agreement for friction factor and Nusselt number. The methodology is then applied to a generic heatshield geometry to indicate that a viable computational route has been developed for combustor heatshield analysis.

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