An Experimental Investigation on Friction Coefficient in Plain Journal Bearings During Start-Up

2008 ◽  
Author(s):  
J. Bouyer ◽  
M. Fillon
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Experimental Measurements ◽  
Air Bearings ◽  
Specific Pressure ◽  
Thrust Bearings ◽  
Start Up ◽  
Transient Thermal

The start-up friction coefficient is a parameter which is very useful for engineers who design hydrodynamic bearings. It is most often issued from an approximation. Several studies can be found in the literature on this topic but most of them are concerned with air bearings or are only numerical. Some studies are more general and deal with the transient thermal behaviour in journal bearings as well as in thrust bearings. Other studies deal with the friction coefficient during running, at a fixed rotational speed. The aim of this study is to provide experimental measurements of the bush torque during start-up of plain journal bearings, varying the specific pressure. Thus, the friction coefficient at start-up (deduced from measurements) is obtained for four different bearings varying feeding conditions, radial clearance and length.

Optimum Design of Multiple-Hole Inherently Compensated Air Bearings—Part 1: Circular Thrust Bearings

1975 ◽  
Vol 97 (2) ◽  
pp. 221-227 ◽  
Author(s):  
S. Eshghy
Keyword(s):  
Optimum Design ◽  
Flow Model ◽  
Dynamic Pressure ◽  
Journal Bearings ◽  
Entrance Region ◽  
Experimental Measurements ◽  
Partial Recovery ◽  
Air Bearings ◽  
Normal Stiffness ◽  
Thrust Bearings

Analyses of inherently compensated hydrostatic gas bearings of three types are presented. The flow model incorporates empirically the partial recovery of the dynamic pressure in the entrance region. Conditions leading to maximum normal stiffness or/and load are given for air. Analytical results are compared with experimental measurements. Circular thrust bearings are discussed in this article. Subsequent papers will deal with collar thrust and journal bearings.

Experimental Investigation of Prototype Water-Lubricated Compliant Foil Bearings

2011 ◽  
Vol 490 ◽  
pp. 97-105 ◽  
Author(s):  
Artur Olszewski ◽  
Michał Wodtke ◽  
Piotr Hryniewicz
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Gas Turbines ◽  
High Speed ◽  
Journal Bearings ◽  
Radial Load ◽  
Sliding Speed ◽  
Good Tolerance ◽  
Foil Bearings ◽  
Water Pumps

First gas-lubricated compliant foil bearings (CFBs) were built in the 1950s. Due to their significant advantages, such as oil-free operation, good tolerance to bearing misalignment and very low maintenance, they have been penetrating the bearing applications for high speed compressors, air-cycle machines and gas turbines. The work presented here investigates a novel idea of water-lubricated compliant foil bearings, which could be used in applications where environmentally friendly lubrication is desired, for example in hydroelectric turbines or water pumps. Experimental results collected for three prototype water-lubricated foil journal bearings are presented. The tests were conducted under steady radial load and with the sliding speed varied incrementally. A sequence of design improvements is presented, with the best bearing demonstrating friction coefficient of about 0.01 at the sliding speed of about 4 m/s and the radial load of about 300 kPa. Encountered difficulties, research methodology and the testing equipment are also described.

Dynamic Film Pressure Measurements in Journal Bearings for Use in Rotor Balancing

1976 ◽  
Vol 98 (1) ◽  
pp. 92-100 ◽  
Author(s):  
E. Christensen ◽  
J. Tonnesen ◽  
J. W. Lund
Keyword(s):  
Experimental Investigation ◽  
Measurement Accuracy ◽  
Journal Bearing ◽  
Linear Analysis ◽  
Journal Bearings ◽  
Experimental Measurements ◽  
Pressure Measurements ◽  
Pressure Transducers ◽  
Theoretical Predictions ◽  
Rotor Balancing

The paper presents the results of an experimental investigation where membrane transducers in the journal bearing wall are used to measure the dynamic oil-film pressures caused by rotor unbalance whirl. The results are applied successfully to balancing the rotor, and the experimental measurements of amplitude and pressure response are found to agree well with theoretical predictions, based on a linear analysis. The measurement accuracy of the pressure transducers compare favorably with the accuracy obtained with shaft displacement probes.

Journal Bearing Lubrication and Design

1948 ◽  
Vol 158 (1) ◽  
pp. 250-254
Author(s):  
A. S. T. Thomson
Keyword(s):  
Experimental Investigation ◽  
Applied Load ◽  
Journal Bearing ◽  
Point Contact ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Experimental Results ◽  
Radial Clearance ◽  
Series Of Experiments ◽  
Loaded Side

The paper summarizes the results of an experimental investigation on the effects of variation in bearing width and radial clearance on the operating conditions of centrally loaded clearance journal bearings, the bearing arc being kept constant at 120 deg. The investigation, which was carried out prior to 1940, is complementary to an earlier paper by the author in which the effects of variations in bearing width and arc of embrace were investigated. The experimental results are compared with theoretical values modified by the relevant leakage coefficients. The measure of agreement obtained indicates that theoretical values so modified may be used with confidence in design. A short series of experiments is described; in these, high-point contact at starting and stopping is eliminated by supplying oil to a groove in the loaded side of the bearing at a pressure sufficiently great to overcome the applied load. The effect of a groove on the loaded side of the brass under various conditions of lubrication is investigated.

scholarly journals A Simple Mechanistic Model for Friction of Rough Partially Lubricated Surfaces

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
Gianluca Costagliola ◽  
Tobias Brink ◽  
Julie Richard ◽  
Christian Leppin ◽  
Aude Despois ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Coefficient ◽  
Mechanistic Model ◽  
Applied Pressure ◽  
Real Contact Area ◽  
Experimental Measurements ◽  
Dynamic Friction ◽  
Real Contact ◽  
Dynamic Friction Coefficient ◽  
Direct Measurements

AbstractWe report experimental measurements of friction between an aluminum alloy sliding over steel with various lubricant densities. Using the topography scans of the surfaces as input, we calculate the real contact area using the boundary element method and the dynamic friction coefficient by means of a simple mechanistic model. Partial lubrication of the surfaces is accounted for by a random deposition model of oil droplets. Our approach reproduces the qualitative trends of a decrease of the macroscopic friction coefficient with applied pressure, due to a larger fraction of the micro-contacts being lubricated for larger loads. This approach relates direct measurements of surface topography to realistic distributions of lubricant, suggesting possible model extensions towards quantitative predictions.

scholarly journals Experimental and Numerical Investigation about Small Clearance Journal Bearings under Static Load Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Carlo Alberto Niccolini Marmont Du Haut Champ ◽  
Fabrizio Stefani ◽  
Paolo Silvestri
Keyword(s):  
Three Dimensional ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Small Scale ◽  
Test Rig ◽  
Small Clearance ◽  
Dimensional Simulation ◽  
Dynamic Loading Conditions ◽  
Static And Dynamic Loading ◽  
Good Agreement

The aim of the present research is to characterize both experimentally and numerically journal bearings with low radial clearances for rotors in small-scale applications (e.g., microgas turbines); their diameter is in the order of ten millimetres, leading to very small dimensional clearances when the typical relative ones (order of 1/1000) are employed; investigating this particular class of journal bearings under static and dynamic loading conditions represents something unexplored. To this goal, a suitable test rig was designed and the performance of its bearings was investigated under steady load. For the sake of comparison, numerical simulations of the lubrication were also performed by means of a simplified model. The original test rig adopted is a commercial rotor kit (RK), but substantial modifications were carried out in order to allow significant measurements. Indeed, the relative radial clearance of RK4 RK bearings is about 2/100, while it is around 1/1000 in industrial bearings. Therefore, the same original RK bearings are employed in this new test rig, but a new shaft was designed to reduce their original clearance. The new custom shaft allows to study bearing behaviour for different clearances, since it is equipped with interchangeable journals. Experimental data obtained by this test rig are then compared with further results of more sophisticated simulations. They were carried out by means of an in-house developed finite element (FEM) code, suitable for thermoelasto-hydrodynamic (TEHD) analysis of journal bearings both in static and dynamic conditions. In this paper, bearing static performances are studied to assess the reliability of the experimental journal location predictions by comparing them with the ones coming from already validated numerical codes. Such comparisons are presented both for large and small clearance bearings of original and modified RKs, respectively. Good agreement is found only for the modified RK equipped with small clearance bearings (relative radial clearance 8/1000), as expected. In comparison with two-dimensional lubrication analysis, three-dimensional simulation improves prediction of journal location and correlation with experimental results.

Observation of Cracks of PEEK Polymer Thrust Bearings under Rolling Contact Fatigue in Water

2016 ◽  
Vol 703 ◽  
pp. 172-177 ◽  
Author(s):  
Xiao Chen Shi ◽  
Masaya Orito ◽  
Yuji Kashima ◽  
Koshiro Mizobe ◽  
Katsuyuki Kida
Keyword(s):  
Corrosion Resistance ◽  
Friction Coefficient ◽  
Cross Sections ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Light Weight ◽  
Low Friction ◽  
High Corrosion Resistance ◽  
Thrust Bearings

Considering the advantages on light weight, low friction coefficient, high corrosion resistance and electric insulation, polymer bearings are widely used under certain environments, where the toughness like metal bearings is not necessary. In our previous study, it was concluded that the main reason for PEEK thrust bearings failure in water was flaking due to surface crack propagation. In the present study, crack observations were made on groove surfaces and cross sections along both radial and rolling directions in order to find the relation between cracks and flaking failures.

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