Paper 8: A Graphical Method for Predicting the Performance of Circumferentially Grooved Hydrodynamic Journal Bearings under Steady Loads

1965 ◽  
Vol 180 (11) ◽  
pp. 160-173
Author(s):  
F. A. Martin
Keyword(s):  
Iterative Process ◽  
Journal Bearing ◽  
Graphical Method ◽  
Design Method ◽  
Simultaneous Equations ◽  
Eccentricity Ratio ◽  
Normal Manner ◽  
Oil Flow ◽  
Bearing Design ◽  
Inlet Conditions

This paper illustrates a procedure of bearing design which avoids the iterative process of conventional methods of determining the eccentricity ratio in a journal bearing. The iterative process results from the need to satisfy three simultaneous equations; in the method described, the equations are graphically defined on two sheets. The transparent sheet defines the bearing data and eccentricity ratio and the opaque sheet defines the viscosity-temperature characteristics of the oil chosen. The transparent sheet is moved over the opaque sheet according to a fixed locus till a point representing the bearing data is coincident with the oil inlet conditions. The eccentricity ratio can be read directly and power loss and oil flow calculations may then be carried out in the normal manner. Experimental results obtained from tests with circumferentially grooved bearings have been used to test the generality of the design method and also to check the assumptions relating to operating viscosities in the bearing.

scholarly journals Towards Investigation of External Oil Flow From a Journal Bearing in an Epicyclic Gearbox

2017 ◽  
Author(s):  
Martin Berthold ◽  
Hervé Morvan ◽  
Colin Young ◽  
Richard Jefferson-Loveday
Keyword(s):  
Flow Field ◽  
Journal Bearing ◽  
Numerical Models ◽  
Flow Behavior ◽  
Phase Interface ◽  
Journal Bearings ◽  
Field Behavior ◽  
Oil Flow ◽  
Inlet Conditions ◽  
Near Wall

High loads and bearing life requirements make journal bearings the preferred choice for use in high power, epicyclic gearboxes in jet engines. In contrast to conventional, non-orbiting journal bearings in epicyclic star gearboxes, the kinematic conditions in epicyclic planetary arrangements are much more complex. With the planet gears rotating about their own axis and orbiting around the sun gear, centrifugal forces generated by both motions interact with each other and affect the external flow behavior of the oil exiting the journal bearing. This paper presents a literature and state-of-the-art knowledge review to identify existing work performed on cases similar to external journal bearing oil flow. In order to numerically investigate external journal bearing oil flow, an approach to decompose an actual journal bearing into simplified models is proposed. Later, these can be extended in a step-wise manner to allow key underlying physical phenomena to be identified. Preliminary modeling considerations will also be presented. This includes assessing different geometrical inlet conditions with the aim of minimizing computational requirements and different numerical models for near-wall treatment. The correct choice of near-wall treatment models is particularly crucial as it determines the bearing’s internal and external thermal behavior and properties. The findings and conclusions are used to create a three dimensional (3D), two-component computational fluid dynamic (CFD) sector model with rotationally periodic boundaries of the most simplistic approximation of an actual journal bearing: a non-orbiting representation, rotating about its own axis, with a circumferentially constant, i.e. concentric, lubricating gap. The inlet boundary conditions for simulating the external oil flow are generated by partly simulating the internal oil flow within the lubricating gap. In order to track the phase interface between the oil and the air surrounding the bearing, the Volume of Fluid (VoF) method is used. The quality of the CFD simulations of the domain of interest is not only dependent on the accuracy of the inlet conditions, but is also dependent on the computational mesh type, cell count, cell shape and numerical methods used. External journal bearing oil flow was simulated with a number of different mesh densities and the effect on the flow field behavior will be discussed. Two different operating temperatures, representing low and high viscosity oil, were used and their effect on the flow field behavior will also be assessed. In order to achieve the future objective of creating a design tool for routine use, key areas will be identified in which further progress is required. This includes the need to progressively increase the model fidelity to eventually simulate an orbiting journal bearing in planetary configuration with an eccentric, i.e. convergent-divergent, lubricating gap.

A Thermohydrodynamic Lubrication Analysis to Design Large Two-Pad Journal Bearing With Cooling Ditches

1998 ◽  
Vol 120 (2) ◽  
pp. 214-220 ◽  
Author(s):  
S. Taniguchi ◽  
T. Makino ◽  
Y. Ozawa ◽  
T. Ichimura
Keyword(s):  
Electric Utilities ◽  
Journal Bearing ◽  
Flow Analysis ◽  
Simultaneous Equations ◽  
Pump Performance ◽  
Full Size ◽  
Viscous Pump ◽  
Oil Flow ◽  
Near Future ◽  
Good Agreement

A newly developed large two-pad journal bearing with cooling ditches and viscous pump for turbines of electric utilities was analyzed theoretically. The turbulent thermohydrodynamic lubrication analysis was done in connection with the flow analysis of oil circulating system through the cooling ditches and the viscous pump. The complicated simultaneous equations concerned with the oil flow in the bearing were solved and used to design a bearing of 535 mm diameter which will make its appearance in a near future. Full size bearing tests were carried out to check the bearing performance and viscous pump performance and to confirm the accuracy of the calculation method. Good agreement was obtained between the theoretical and experimental results.

Numerical investigation of dynamic and hydrodynamic characteristics of the pad in the fluid pivot journal bearing

2021 ◽  
pp. 135065012110330
Author(s):  
Tuyen Vu Nguyen ◽  
Weiguang Li
Keyword(s):  
Computational Models ◽  
Journal Bearing ◽  
Squeeze Film ◽  
Hydrodynamic Characteristics ◽  
Hydrodynamic Properties ◽  
Squeeze Film Damper ◽  
Lubricant Oil ◽  
Oil Flow ◽  
Flow Through ◽  
Bearing System

The dynamic and hydrodynamic properties of the pad in the fluid pivot journal bearing are investigated in this paper. Preload coefficients, recess area, and size gap, which were selected as input parameters to investigate, are important parameters of fluid pivot journal bearing. The pad’s pendulum angle, lubricant oil flow through the gap, and recess pressure which characterizes the squeeze film damper were investigated with different preload coefficients, recess area, and gap sizes. The computational models were established and numerical methods were used to determine the equilibrium position of the shaft-bearing system. Since then, the pendulum angle of the pad, liquid flow, and recess pressure were determined by different eccentricities.

scholarly journals Pivoted-Pad Journal Gas Bearing Performance in Exploratory Operation of Brayton Cycle Turbocompressor

1968 ◽  
Vol 90 (4) ◽  
pp. 687-696 ◽  
Author(s):  
R. Y. Wong ◽  
W. L. Stewart ◽  
H. E. Rohlik
Keyword(s):  
Experimental Study ◽  
Journal Bearing ◽  
Inert Gas ◽  
Brayton Cycle ◽  
Ambient Conditions ◽  
Operating Characteristics ◽  
The Third ◽  
Loading Device ◽  
Bearing Design ◽  
Gas Bearing

This paper describes findings obtained to date in the area of journal gas bearings from an experimental study of a Brayton cycle turbocompressor designed for the requirements of a two-shaft 10-kw space power system. The journal bearing design utilizes three pads pivoted on conforming balls and sockets. Two of the pivots are rigidly mounted to the frame, and the third pivot is mounted to the frame through a low-spring-rate diaphragm. This paper describes the salient package and bearing design features and then presents the principal results obtained from testing the package in both a spin calibration rig and operation at design temperature conditions with an inert gas. The results discussed include (a) the successful use of a pneumatic loading device to vary pad load during operation, (b) the operating characteristics of the bearings as obtained over a range of pad loads and ambient conditions, (c) structural and dynamic behavior of the bearing-support system during design temperature operation and (d) a discussion of the wear characteristics of the conforming ball-and-socket pivot as obtained from the tests made to date.

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

scholarly journals Multiphase CFD Modeling of External Oil Flow From a Journal Bearing

2018 ◽  
Author(s):  
Martin Berthold ◽  
Hervé Morvan ◽  
Richard Jefferson-Loveday ◽  
Benjamin C. Rothwell ◽  
Colin Young
Keyword(s):  
Boundary Conditions ◽  
Journal Bearing ◽  
Flow Behavior ◽  
Phase Interface ◽  
Numerical Schemes ◽  
Ansys Fluent ◽  
Oil Film ◽  
Reconstruction Scheme ◽  
Geometric Reconstruction ◽  
Oil Flow

High loads and bearing life requirements make journal bearings a potential choice for use in high power, epicyclic gearboxes in jet engines. Particularly in a planetary configuration the kinematic conditions are complex. With the planet gears rotating about their own axis and orbiting around the sun gear, centrifugal forces generated by both motions interact with each other and affect the external flow behavior of the oil exiting the journal bearing. Computational Fluid Dynamics (CFD) simulations using the Volume of Fluid (VoF) method are carried out in ANSYS Fluent [1] to numerically model the two-phase flow behavior of the oil exiting the bearing and merging into the air surrounding the bearing. This paper presents an investigation of two numerical schemes that are available in ANSYS Fluent to track or capture the air-oil phase interface: the geometric reconstruction scheme and the compressive scheme. Both numerical schemes are used to model the oil outflow behavior in the most simplistic approximation of a journal bearing: a representation, rotating about its own axis, with a circumferentially constant, i.e. concentric, lubricating gap. Based on these simplifications, a three dimensional (3D) CFD sector model with rotationally periodic boundaries is considered. A comparison of the geometric reconstruction scheme and the compressive scheme is presented with regards to the accuracy of the phase interface reconstruction and the time required to reach steady state flow field conditions. The CFD predictions are validated against existing literature data with respect to the flow regime, the direction of the predicted oil flow path and the oil film thickness. Based on the findings and considerations of industrial requirements, a recommendation is made for the most suitable scheme to be used. With a robust and partially validated CFD model in place, the model fidelity can be enhanced to include journal bearing eccentricity. Due to the convergent-divergent gap and the resultant pressure field within the lubricating oil film, the outflow behavior can be expected to be very different compared to that of a concentric journal bearing. Naturally, the inlet boundary conditions for the oil emerging from the journal bearing into the external environment must be consistent with the outlet conditions from the bearing. The second part of this paper therefore focuses on providing a method to generate appropriate inlet boundary conditions for external oil flow from an eccentric journal bearing.

Effects of Freestream Turbulence on the Losses of a Highly-Loaded Compressor Stator Blade

2003 ◽  
Author(s):  
J. W. Douglas ◽  
S.-M. Li ◽  
B. Song ◽  
W. F. Ng ◽  
Toyotaka Sonoda ◽  
...  
Keyword(s):  
Turbulence Intensity ◽  
Flow Separation ◽  
Reynolds Numbers ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Flow Losses ◽  
Oil Flow ◽  
Oil Flow Visualization ◽  
Inlet Conditions ◽  
High Reynolds

Very little published literature documents the effects of different freestream turbulence intensities on compressor flows at realistically high Reynolds numbers. This paper presents a study of these effects on a transonic, linear, compressor stator cascade. The cascade consisted of high turning stator airfoils that had the camber of 55 degrees. The effects of freestream turbulence intensities of approximately 0.1% (baseline) and 1.6% were examined. Inlet Mach numbers to the cascade were tested from 0.55 to 0.89. Reynolds numbers, based on the inlet conditions and blade chord, varied between 1.0–2.0×106. Inlet flow angles to the cascade ranged from a choking to a stall condition. For the baseline cases, at most positive incidence angles to the cascade, surface oil flow visualization and Schlieren pictures showed a significant flow separation on the suction surface of the blade. Under these conditions, the increase in freestream turbulence from 0.1% to 1.6% significantly reduced the flow losses of the cascade (by as much as 57% in some cases). In other test conditions where no evidence depicted flow separation on the blade, there were no measurable effects on the losses due to the increase in freestream turbulence intensity. In addition, the increase of freestream turbulence intensity also improved the effective operating range of the cascade significantly (e.g., by 46% or higher).

A Design of Coverage Area for Textured Surface of Sliding Journal Bearing Based on Genetic Algorithm

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Hui Zhang ◽  
Mahshid Hafezi ◽  
Guangneng Dong ◽  
Yang Liu
Keyword(s):  
Genetic Algorithm ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Textured Surface ◽  
The Novel ◽  
Eccentricity Ratio ◽  
Coverage Area ◽  
Elliptical Shape ◽  
Bearing Load ◽  
Rectangular Grids

This paper aims to improve the tribological performance of journal bearings by optimizing the coverage area of circular microtextures in divergent region of the sleeve. A numerical model is proposed to calculate the friction coefficient and bearing load of textured journal bearings. The surface of the sleeve is divided into rectangular squares. Textures that located at the center of rectangular grids are assumed to be present or absent, marked as 1 and 0, respectively. Afterward, different texture coverage area arrangements are evolved and selected based on the genetic algorithm (GA). The area of semi-elliptical shape is obtained as the novel and preferable textured coverage area design for journal bearings. Influences of width and eccentricity ratio are discussed, which confirm the semimajor and semiminor axes of the semi-elliptical shape of texture coverage area equal to one-third of the circumferential length and half of the width of the journal bearing, respectively.

scholarly journals CFD analysis of partial slip effect on the performance of hydrodynamic lubricated journal bearings

2018 ◽  
Vol 204 ◽  
pp. 04014
Author(s):  
Muchammad ◽  
Bambang Yunianto ◽  
Mohammad Tauviqirrahman ◽  
Widhi Ahmad Wicaksono ◽  
Jamari
Keyword(s):  
Journal Bearing ◽  
Fluid Dynamic ◽  
Hydrodynamic Performance ◽  
Partial Slip ◽  
Cfd Analysis ◽  
Eccentricity Ratio ◽  
Hydrophobic Coating ◽  
Lubrication Performance ◽  
Slip Area ◽  
Increasing Load

Slip modification of the lubricated bearing such hydrophobic coating has proven to improve the hydrodynamic performance. The present paper investigates the effect of partial slip on the journal bearing performance using computational fluid dynamic (CFD) approach. The eccentricity ratio and the placement of slip area are of particular interest. It was shown that the partial slip placement on the convergent region of the bearing generally improves the hydrodynamic performance lubrication by increasing load support. It was also found that introducing partial slip on the divergent area decreases the lubrication performance of journal bearing.

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