AN ANALYSIS OF THE INFLUENCE OF JOURNAL’S HELICAL GROOVE ON THE WEAR AND LOAD CAPACITY OF THE SLIDING BEARING

Tribologia ◽  
2016 ◽  
Vol 268 (4) ◽  
pp. 191-199
Author(s):  
Leszek TOMCZEWSKI ◽  
Jarosław SĘP
Keyword(s):  
Load Capacity ◽  
Journal Bearings ◽  
Sliding Bearing ◽  
Hard Particles ◽  
Effective Reduction ◽  
Oil Flow ◽  
Helical Groove ◽  
Helical Grooves ◽  
Wear Tests ◽  
Contaminated Lubrication

The article presents the results of a sliding bearing with a helical groove on a journal. The studies included wear tests with contaminated lubrication oil and computer simulation of oil flow based on which the load capacity of a bearing was determined. The 7 bearings with different variants of helical grooves on journal bearings and classical bearings were studied. It was found that the helical groove on the journal makes it possible to significantly reduce the wear of the bearing in the case of oil contamination with hard particles. It was also shown that the groove on the journal ensures an effective reduction in wear and does not result in a significant reduction of load capacity.

THE EFFECT OF HELICAL GROOVE PRESENCE ON THE TRIBOLOGICAL PERFORMANCE OF JOURNAL BEARINGS

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 131-138
Author(s):  
Jarosław SĘP ◽  
Leszek TOMCZEWSKI ◽  
Lidia GAŁDA
Keyword(s):  
Load Capacity ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Equation System ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Static Characteristics ◽  
Hydrodynamic Bearings ◽  
Oil Flow ◽  
Helical Groove

The hydrodynamic bearings could suffer critical damages operating in contaminated environments that cause machine breakdown. In such hard operating conditions, hydrodynamic bearings with grooved journals are less sensitive to damage compared to plain bearings. The wear resistance of the grooved journal bearings is several times greater than that of smooth journal bearings. Contaminants existing in the oil film are moved out from the bearing clearance by the groove created on the journal surface. The presence, shape, and geometry of the groove strongly influence the bearings performance. The aim of this article is to study the selected static characteristics of bearings consisting of a journal with the helical groove on its surface. The static characteristics were determined based on the flow simulation in the oil clearance. A three-dimensional, adiabatic model of the oil flow was assumed. The oil flow was described with the Navier-Stokes continuity and energy equations. The equation system was solved by the finite volume method. The numerical model of the flow was verified experimentally on a test stand. It has been established that the grooved journal application leads to a decrease of load capacity in whole range of eccentricity and for all examined clearances. The oil flow rate increase was mainly observed due to spiral groove presence on the shaft.

Rotordynamic and Bearing Upgrade of a High-Speed Turbocharger

2001 ◽  
Author(s):  
Brian C. Pettinato ◽  
Pranabesh DeChoudhury
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Flow Distribution ◽  
Journal Bearings ◽  
Original Design ◽  
Thrust Bearings ◽  
Vibration Data ◽  
Bearing Life ◽  
Oil Flow

The paper discusses the redesign of a high-speed turbocharger for improved bearing life and mechanical operation. The modifications resulted in reduced oil leakage across the end seal, reduced coke buildup at the turbine, increased thrust load capacity, and improved rotordynamics. In particular, rotordynamic stability was improved by eliminating subsynchronous vibration at the operating speed. The redesign consisted of changing the bearings from a pair of combination journal/thrust bearings to a pair of journal bearings and a double acting thrust bearing at the center of the unit. The active thrust bearing was moved away from the hot turbine end of the machine. The thrust bearing geometry was modified for increased minimum film thickness, reduced metal temperature, and increased load capacity. Inlet and drain passages were revised for better oil flow distribution. Unit rotordynamics were improved by upgrading the journal bearings from three-axial-groove to three-lobe design. The upgraded unit kept the same footprint as the original design with only piping modifications required. Extensive analysis and testing were conducted. Testing of the original and revised turbochargers showed improvements in the redesign with reduced bearing metal temperatures and improved rotordynamic stability. Theoretical results along with test data consisting of bearing performance and vibration data of the original and modified system are presented in this paper.

Dynamic Performance of Oil-Lubricated Helical Groove Journal Bearings

1994 ◽  
Vol 208 (1) ◽  
pp. 65-73 ◽  
Author(s):  
M Z Khan ◽  
T A Stolarski
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Eccentricity Ratio ◽  
Power Losses ◽  
Helical Groove ◽  
Higher Temperature ◽  
The Stability ◽  
Helical Grooves ◽  
Theoretical Results

The provision of helical grooves on the surface of a plain journal bearing can, in principle, improve the stability of a rotor-bearing system. The improvement, however, depends on the arrangement of the grooves along the axial length of the bearing. In order to verify this, three types of helical groove bearing with different groove arrangements and a reference plain journal bearing were studied. The bearings were studied in a specially designed test rig. A computer model was also developed to predict the performance of the bearings studied. The experimental and theoretical results produced during the course of the studies show that at the expense of a reduced load capacity the helical groove bearings are more stable, particularly at low eccentricity ratios. For a given eccentricity ratio and speed the symmetrical bearing operates at higher temperature and with greater power losses than the other three bearings tested. At the same eccentricity ratio and speed, the asymmetrical bearing runs at about the same temperature as the plain journal bearing.

Static Characteristics of Low Speed Cylindrical Journal Bearings of the Rope Wheel of Hoist Tower

2005 ◽  
Author(s):  
S. Strzelecki ◽  
W. Wojcicki ◽  
W. Famulski
Keyword(s):  
Load Capacity ◽  
Journal Bearings ◽  
Static Characteristics ◽  
Rolling Bearings ◽  
Oil Film ◽  
Low Speed ◽  
Oil Flow ◽  
Bearing Design ◽  
Bearing System ◽  
Oil Film Pressure

The design solutions of bearings carrying the shafts of rope wheels on the hoist tower of coal mines consists the rolling bearings or plain journal ones. Plain journal bearings allow for easy assembling and for smooth operation without vibrations. Static characteristics of journal bearings consist of oil film pressure and temperature distributions, static equilibrium position angles, load capacity, oil flow and power loss and their knowledge is the basis of bearing design. The paper comprises the static characteristics of low speed cylindrical journal bearings that are applied in the bearing system of the rope wheels of hoist tower. The calculations of these characteristics were carried-out on the assumption of adiabatic oil film.

An Approximate THD Theory for Journal Bearings

1990 ◽  
Vol 112 (2) ◽  
pp. 224-229 ◽  
Author(s):  
G. Gupta ◽  
C. R. Hammond ◽  
A. Z. Szeri
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Pressure Coefficient ◽  
Journal Bearings ◽  
Maximum Pressure ◽  
Substantial Agreement ◽  
Interactive Mode ◽  
Lubricant Flow ◽  
Bearing Load ◽  
Sophisticated Model

The aim of this paper is to make available to the industrial designer results of the thermohydrodynamic theory of journal bearings, by providing a simplified, yet accurate model of journal bearing lubrication that can be implemented on a personal computer and be used in an interactive mode. The simplified THD theory we propose consists of two coupled ordinary differential equations for pressure and energy and an algebraic equation for viscosity, which are to be solved iteratively. Bearing load capacity, maximum bearing temperature, maximum pressure, coefficient of friction and lubricant flow rate calculated from this simplified theory compare well with results from a more sophisticated model. We also make comparisons with experimental data on full journal bearings, demonstrating substantial agreement between experiment and simplified theory.

Geometric Effects on Eddy Current Bearing Performance

1989 ◽  
Vol 111 (2) ◽  
pp. 209-214 ◽  
Author(s):  
J. A. Tichy ◽  
K. A. Connor
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Load Capacity ◽  
Complex Mixture ◽  
Journal Bearings ◽  
Magnetic Bearings ◽  
Repulsive Forces ◽  
The Magnetic Field ◽  
Geometric Effects ◽  
Current Journal

The properties of magnetic bearings, particularly those based on repulsive forces due to eddy currents, are determined by a complex mixture of electrical and mechanical length and time scales. A perturbation solution for the magnetic field structure based on careful ordering of these parameters has permitted the effects of realistic gap geometries to be analyzed. The load capacity of eddy current journal bearings is found to be somewhat larger than previously predicted in an earlier paper which used magnetic fields based on constant gap size. The present results may be of interest to those concerned with calculating eddy currents in conventional attractive magnetic bearings.

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.

Design of Multi-Recess Hydrostatic Journal Bearings for Minimum Total Power Loss

1974 ◽  
Vol 96 (1) ◽  
pp. 226-232 ◽  
Author(s):  
C. Cusano ◽  
T. F. Conry
Keyword(s):  
Rotational Speed ◽  
Power Loss ◽  
Load Capacity ◽  
Maximum Load ◽  
Journal Bearings ◽  
Design Criterion ◽  
Total Power ◽  
Eccentricity Ratio ◽  
Constant Ratio ◽  
Design Charts

The design problem is formulated for multi-recess hydrostatic journal bearings with a design criterion of minimum total power loss. The design is subject to the constraints of constant ratio of the recess area to the total bearing area and maximum load capacity for a given recess geometry. The L/D ratio, eccentricity ratio, ratio of recess area to total bearing area, and shaft rotational speed are considered as parameters. The analysis is based on the bearing model of Raimondi and Boyd [1]. This model is generally valid for low-to-moderate speeds and a ratio of recess area-to-total bearing area of approximately 0.5 or greater. Design charts are presented for bearings having a ratio of recess area-to-total bearing area of 0.6 and employing capillary and orifice restrictors, these being the most common types of compensating elements. A design example is given to illustrate the use of the design charts.

Lubrication of Porous Journal Bearings

1972 ◽  
Vol 94 (1) ◽  
pp. 69-73 ◽  
Author(s):  
C. Cusano
Keyword(s):  
Analytical Solution ◽  
Coefficient Of Friction ◽  
Load Capacity ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Eccentricity Ratio ◽  
Design Variables

An analytical solution for the performance characteristics of finite porous journal bearings is obtained. Results are presented which relate the eccentricity ratio and coefficient of friction as functions of load number for design variables of 0.0001, 0.001, 0.01, and 0.1. The load capacity obtained by using the finite bearing theory is compared to the load capacity obtained by using the short-bearing approximation and the infinite-bearing approximation.

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