scholarly journals Observation of Pressure Variation in the Cavitation Region of Submerged Journal Bearings

1982 ◽  
Vol 104 (2) ◽  
pp. 157-163 ◽  
Author(s):  
I. Etsion ◽  
L. P. Ludwig
Keyword(s):  
Journal Bearing ◽  
Reverse Flow ◽  
Ambient Pressure ◽  
Journal Bearings ◽  
Pressure Variation ◽  
Pressure Measurements ◽  
Pressure Profiles ◽  
Cavitation Region ◽  
Cavitation Pressure ◽  
Visual Observations

Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests were performed at various shaft speeds and ambient pressure levels. Some photographs of the cavitation region are presented showing strong reverse flow at the downstream end of the region. Pressure profiles are presented showing significant pressure variations inside the cavitation zone, contrary to common assumptions of constant cavitation pressure.

Cavitation Boundary Shapes for Submerged Short Journal Bearings Using Newtonian Lubricants

1985 ◽  
Vol 52 (4) ◽  
pp. 771-776 ◽  
Author(s):  
R. H. Buckholz
Keyword(s):  
Boundary Condition ◽  
Slenderness Ratio ◽  
Leading Edge ◽  
Journal Bearings ◽  
Surface Boundary ◽  
Lubrication Equation ◽  
Free Surface Boundary Condition ◽  
Cavitation Region ◽  
Cavitation Pressure ◽  
Surface Boundary Condition

Cavitation boundary shapes for submerged short journal bearings are investigated in this study. In this analysis, the Reynolds lubrication equation is approximated by using the bearing slenderness ratio as a small parameter. The slenderness ratio appears explicitly in the Reynolds lubrication equation. The lubrication equation is solved subjected to the boundary condition of a subambient value for the cavitation pressure and the additional Reynolds’ free-surface boundary condition along the unknown cavitation boundary. The Ocvirk short bearing solution is shown to fail near the leading edge of the cavitation region, and a matched asymptotic theory is used to determine the shape and location of this cavitated region. Cavitation bubble location and size are shown to depend on bearing aspect ratio, journal eccentricity, and cavitation pressure. Finally the present journal bearing analysis is limited to those cases where the cavitation region has a large axial extent.

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.

Prediction of Temperature Fade in the Cavitation Region of Two-Lobe Journal Bearings

1994 ◽  
Vol 208 (2) ◽  
pp. 133-139 ◽  
Author(s):  
M-T Ma ◽  
C M Taylor
Keyword(s):  
Experimental Evidence ◽  
Heat Balance ◽  
Present Method ◽  
Model Comparison ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Cavitation Model ◽  
Back Flow ◽  
Cavitation Region ◽  
Theory And Experiment

Experimental evidence has shown that there often exists a considerable drop in bush temperature (the so-called temperature fade) in the cavitation region of journal bearings. This is contrary to the predictions of the conventional thermohydrodynamic analyses which give more or less rising temperatures. In order to bring theory into accord with experiment, an elemental heat-balance method was established by the authors to predict the temperatures in the cavitation region of two-lobe journal bearings. In this approach, the effect of oil back-flow from feed grooves was included on the basis of the separation cavitation model. Comparison between theory and experiment for a two-axial-groove circular bearing and an elliptical bearing has indicated that the present method is very effective in predicting the temperature fade. The analysis for the prediction of temperatures in the exit cavitation region is in principle applicable to multi-lobe journal bearing situations.

Advancements in the Performance of Aerodynamic Foil Journal Bearings: High Speed and Load Capability

1994 ◽  
Vol 116 (2) ◽  
pp. 287-294 ◽  
Author(s):  
H. Heshmat
Keyword(s):  
High Speed ◽  
Room Temperature ◽  
Journal Bearing ◽  
Load Capacity ◽  
Ambient Pressure ◽  
Journal Bearings ◽  
Test Results ◽  
Rotor Speed ◽  
Turbine Wheel ◽  
Dynamic Analyses

An advanced-design, aerodynamic, air-lubricated foil journal bearing achieved a landmark speed of 2200 cps (132,000 rpm) and a major breakthrough in load performance of 673.5 kPa (97.7 psi). At 20°C (68°F) room temperature, normal ambient pressure, 995 cps (59,700 rpm) rotor speed, and with bearing projected pad area of 1081 mm2 (1.675 in2), the bearing demonstrated a load capacity of 727.8 N (163.6 lb). The bearing also exhibited low heat generation, with about 40°C (104°F) average side leakage temperature rise. For this demonstration, a highspeed spindle utilizing a pair of 35-mm (1.375-in.) bearings and supporting a test rotor with a mass of 1.545 kg (weighing 3.41 lb) and overall length of 211 mm (8.3 in.) was successfully taken to the limiting speed of the test apparatus. This speed was set by the maximum sound velocity (Mach 1) in the spindle’s turbine wheel. The rotor/bearing speed of 4.62 × 106 DN is beyond the capability of any advanced oil-lubricated ball bearings or conventional gas-lubricated bearings. The net result is a highly stable bearing at high operating speed. This paper presents the development of this air-lubricated foil journal bearing, the operational procedures used during testing, test results (dynamic analyses), and load performance characteristics.

scholarly journals The Prediction of Liquid Film Journal Bearing Performance with a Consideration of Lubricant Film Reformation: Part 2: Experimental Results

1985 ◽  
Vol 199 (2) ◽  
pp. 103-111 ◽  
Author(s):  
D Dowson ◽  
C M Taylor ◽  
A A S Miranda
Keyword(s):  
Experimental Investigation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Lubricant Film ◽  
Plain Bearing ◽  
Operating Characteristics ◽  
Design Data ◽  
Cavitation Region ◽  
Satisfactory Prediction ◽  
Theoretical Results

Analyses and design data for plain journal bearings rarely take into account the phenomenon of film reformation. The consideration of the re-establishment of the lubricant film after the cavitation region is difficult in a number of ways. The importance of allowing for reformation is, however, being increasingly recognized. This is particularly true as regards the satisfactory prediction of lubricant flowrate and the thermal operating characteristics of a bearing. The authors have previously implemented a cavitation algorithm to enable the cavitation region in a plain journal bearing to be located automatically and efficiently in a computer analysis. In Part I of the present paper theoretical results have been presented for the case of a plain bearing with a square-ended, axial groove located at the position of maximum film thickness. The second part of the paper gives details of an experimental investigation designed to establish the validity of the analysis.

Reverse Flow as a Possible Mechanism for Cavitation Pressure Build-up in a Submerged Journal Bearing

2001 ◽  
Vol 124 (2) ◽  
pp. 320-326 ◽  
Author(s):  
M. Groper ◽  
I. Etsion
Keyword(s):  
Pressure Distribution ◽  
Present Model ◽  
Journal Bearing ◽  
Reverse Flow ◽  
Experimental Results ◽  
Flow Mechanism ◽  
Flow Phenomenon ◽  
Cavitation Pressure

An experimentally observed reverse flow phenomenon at the end tip of the cavitation zone of a submerged journal bearing is modeled and theoretically investigated. The shape of the cavity, the nature of the reverse flow and the pressure distribution in the bearing are calculated in an attempt to understand previous experimental observations of pressure build up in the cavitation zone. A comparison with the available experimental results reveals that the cavitation shape, the behavior of the reverse flow and the pressure distribution are fairly well predicted by the present model. The reverse flow mechanism is indeed capable to generate the level of the experimentally measured pressures, particularly towards the end of the cavitation zone.

Thermohydrodynamic Analysis of Journal Bearings Considering Cavitation and Reverse Flow

1988 ◽  
Vol 110 (3) ◽  
pp. 439-447 ◽  
Author(s):  
H. H. Ott ◽  
G. Paradissiadis
Keyword(s):  
Boundary Condition ◽  
Theoretical Model ◽  
Energy Equation ◽  
Journal Bearing ◽  
Reverse Flow ◽  
Iterative Solution ◽  
Journal Bearings ◽  
Flow Area ◽  
Hydrodynamic Journal Bearing ◽  
Energy Equations

The flow field of a hydrodynamic journal bearing is calculated by the iterative solution of the system of Reynolds and energy equations. In the case of reverse flow at the film inlet, the temperature profile there can not be prescribed as a boundary condition but has to be determined from the flow in the film. This is achieved by a separate integration of the energy equation in the reverse flow area. The flow in the cavitation regions is approximated by a theoretical model leading to a form of the energy equation similar to that for pressure regions, thus enabling the integration of the energy equation over the whole film.

Machine learning-based performance analysis of two-axial-groove hydrodynamic journal bearings

2021 ◽  
pp. 135065012199289
Author(s):  
Biswajit Roy ◽  
Sudip Dey
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Hydrodynamic Performance ◽  
Support Vector ◽  
Oil Viscosity ◽  
Hydrodynamic Analysis ◽  
Supply Pressure ◽  
Input Parameters ◽  
Precise Prediction ◽  
Output Behavior

The precise prediction of a rotor against instability is needed for avoiding the degradation or failure of the system’s performance due to the parametric variabilities of a bearing system. In general, the design of the journal bearing is framed based on the deterministic theoretical analysis. To map the precise prediction of hydrodynamic performance, it is needed to include the uncertain effect of input parameters on the output behavior of the journal bearing. This paper presents the uncertain hydrodynamic analysis of a two-axial-groove journal bearing including randomness in bearing oil viscosity and supply pressure. To simulate the uncertainty in the input parameters, the Monte Carlo simulation is carried out. A support vector machine is employed as a metamodel to increase the computational efficiency. Both individual and compound effects of uncertainties in the input parameters are studied to quantify their effect on the steady-state and dynamic characteristics of the bearing.

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.

Characteristics of Herringbone-Grooved, Gas-Lubricated Journal Bearings

1965 ◽  
Vol 87 (3) ◽  
pp. 568-576 ◽  
Author(s):  
J. H. Vohr ◽  
C. Y. Chow
Keyword(s):  
Differential Equation ◽  
Journal Bearing ◽  
Groove Depth ◽  
Radial Force ◽  
Journal Bearings ◽  
Speed Ratio ◽  
Plain Bearing ◽  
Relative Speed ◽  
Whirl Speed ◽  
Limiting Case

A differential equation is obtained for the smoothed “overall” pressure distribution around a herringbone-grooved, gas-lubricated journal bearing operating with a variable film thickness. The equation is based on the limiting case of an idealized bearing for which the number of grooves approaches an infinite number. A numerical solution to the differential equation is obtained valid for small eccentricities. This solution includes the case where the journal is undergoing steady circular whirl. In addition to the usual plain bearing parameters L/D, Λ, and whirl speed ratio ω3/(ω1 + ω2), the behavior of a grooved bearing also depends on four additional parameters: The groove angle β, the relative groove width α, the relative groove depth H0, and a compressibility number, Λs, which is based on the relative speed between the grooved and smooth members of the bearing. Results are presented showing bearing radial force and attitude angle as functions of β, α, H0, Λs, Λ, and whirl speed ratio.

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