Steady-State and Dynamic Analyses of Gas-Lubricated Hybrid Journal Bearings

1969 ◽  
Vol 91 (1) ◽  
pp. 171-180 ◽  
Author(s):  
W. Shapiro
Keyword(s):  
Steady State ◽  
Journal Bearing ◽  
Load Capacity ◽  
External Pressure ◽  
Journal Bearings ◽  
Preliminary Design ◽  
Wide Range ◽  
Dynamic Analyses ◽  
Flow Charts ◽  
Hybrid Bearing

The inherent limitations of load capacity and stability of hydrodynamic gas-lubricated bearings can be reduced by introducing external pressure and creating a hybrid bearing. Numerical computerized analyses of a hybrid journal bearing are discussed; separate developments are presented for steady-state and dynamic characteristics. The steady-state analysis provides performance over a wide range of operating parameters; the more complicated and lengthy dynamic analysis determines stability of the bearing-rotor system using geometry based upon steady-state results. Simplified flow charts of the computer programs are included. The analyses are applied to the preliminary design of a hybrid journal bearing.

Steady-State and Dynamic Behaviour of Multi-Recess Hybrid Oil Journal Bearings

1979 ◽  
Vol 21 (5) ◽  
pp. 345-351 ◽  
Author(s):  
M. K. Ghosh ◽  
B. C. Majumdar ◽  
J. S. Rao
Keyword(s):  
Perturbation Theory ◽  
Steady State ◽  
Theoretical Analysis ◽  
Dynamic Behaviour ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Time Dependent ◽  
Damping Coefficients ◽  
Stiffness And Damping

A theoretical analysis of the steady-state and dynamic characteristics of multi-recess hybrid oil journal bearings is presented. A perturbation theory for small vibrations is used to solve an incompressible, finite journal bearing with a time-dependent term. Load capacity, attitude angle, friction parameter, stiffness and damping coefficients are evaluated for a capillary-compensated bearing.

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.

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.

The Effect of Lubricant Inertia in Journal-Bearing Lubrication

1957 ◽  
Vol 24 (4) ◽  
pp. 494-496
Author(s):  
J. F. Osterle ◽  
Y. T. Chou ◽  
E. A. Saibel
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Hydrodynamic Theory ◽  
Simple Relationship ◽  
Inertia Effect ◽  
Laminar Regime ◽  
Steady State Operation

Abstract The Reynolds equation of hydrodynamic theory, modified to take lubricant inertia into approximate account, is applied to the steady-state operation of journal bearings to determine the effect of lubricant inertia on the pressure developed in the lubricant. A simple relationship results, relating this “inertial” pressure to the Reynolds number of the flow. It is found that the inertia effect can be significant in the laminar regime.

Numerical study on steady state performance enhancement of partial textured hydrodynamic journal bearing

2019 ◽  
Vol 71 (9) ◽  
pp. 1055-1063 ◽  
Author(s):  
Sanjay Sharma ◽  
Gourav Jamwal ◽  
R.K. Awasthi
Keyword(s):  
Steady State ◽  
Journal Bearing ◽  
Performance Enhancement ◽  
Surface Texturing ◽  
Journal Bearings ◽  
Enhancement Ratio ◽  
Content Type ◽  
Maximum Value ◽  
Static Performance ◽  
Hydrodynamic Journal Bearing

Purpose The purpose of this paper is to provide the various steady state parameters of hydrodynamic journal bearings have been determined to get maximum performance enhancement ratio. For this, the bearings inner surface is textured with triangular shape with different texture depths and a number of textures in pressure increasing region. The textured region acts as a lubricant reservoir, which provides additional film-thickness and reduce friction. Therefore, enhance the overall performance of bearing. Design/methodology/approach In the present study, the effect of triangular shaped texture on the static performance characteristics of a hydrodynamic journal bearing has been studied. Different values of texture depths and a number of textures have been numerically simulated in pressure developing region. The static performance characteristics have been calculated by solving the fluid flow governing Reynolds equation using the finite element method, assuming iso-viscous Newtonian fluid. The performance enhancement ratio, which is the ratio of load carrying capacity (LCC) to the coefficient of friction (COF) has been calculated from results to finalized optimum design parameters. Findings The paper provides numerically obtained results indicate that surface texturing can improve bearing performance if the textured region is placed in the pressure increasing region. Moreover, surface texturing is the most effective at bearing performance enhancement when the bearing operates at lower eccentricity ratios and texture depth. The performance enhancement ratio, which is the ratio of LCC to the COF is found to be a maximum value of 2.198 at texture depth of 1.5, eccentricity ratio of 0.2 and the textured region located in the increasing pressure region. Research limitations/implications The present study is based on a numerical based research approach, which has its limitations. So, researchers are encouraged to investigate the same work experimentally. Practical implications The paper includes implications to be beneficial for designers for designing better hydrodynamic journal bearings. Originality/value For the triangular shaped texture, considered in the present study, the optimum values of texture depth and texture distribution region have also been determined. While designing, designers should focus on those values of texture depth, texture region and a number of textures, which give the maximum value of performance enhancement ratio, which represents maximum LCC at the lowest value of the COF.

Theory Versus Experiment for the Effects of Pressure Ratio on the Performance of an Orifice-Compensated Hybrid Bearing

1998 ◽  
Vol 120 (4) ◽  
pp. 930-936 ◽  
Author(s):  
P. Mosher ◽  
D. W. Childs
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Pressure Ratio ◽  
Navier Stokes ◽  
Rotordynamic Coefficients ◽  
Wide Range ◽  
Bearing Load ◽  
Hybrid Bearing

This research investigates the effect of varying the concentric recess pressure ratio of hybrid (combination hydrostatic and hydrodynamic) bearings to be used in high-speed, high-pressure applications. Bearing flowrate, load capacity, torque, rotordynamic coefficients, and whirl frequency ratio are examined to determine the concentric, recess-pressure ratio which yields optimum bearing load capacity and dynamic stiffness. An analytical model, using two-dimensional bulk-flow Navier-Stokes equations and anchored by experimental test results, is used to examine bearing performance over a wide range of concentric recess pressure ratios. Typically, a concentric recess pressure ratio of 0.50 is used to obtain maximum bearing load capacity. This analysis reveals that theoretical optimum bearing performance occurs for a pressure ratio near 0.40, while experimental results indicate the optimum value to he somewhat higher than 0.45. This research demonstrates the ability to analytically investigate hybrid bearings and shows the need for more hybrid-bearing experimental data.

Empirical Treatment of Hydrodynamic Journal Bearing Performance in the Superlaminar Regime

1970 ◽  
Vol 12 (2) ◽  
pp. 116-122 ◽  
Author(s):  
H. F. Black
Keyword(s):  
Reynolds Number ◽  
Field Equation ◽  
Experimental Work ◽  
Reynolds Equation ◽  
Pressure Field ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Theoretical Treatment ◽  
Hydrodynamic Journal Bearing

The application of a perturbation in terms of simple correlations for friction in turbulent Couette and ‘screw’ flows, together with a further empirical assumption consonant with the experimental work of Smith and Fuller (1), leads to a pressure field equation identical in form with the Reynolds equation. The load capacity of journal bearings throughout most of the superlaminar range may be represented by a single curve, and existing laminar solutions may be applied with the parameters modified by Reynolds number. The theory is compared with published experimental results, and with the most successful theoretical treatment (4). The correlations obtained confirm the adequacy of the theory to predict performance in the superlaminar régime.

Measurement of Oil Aeration Effects in Journal Bearings

2002 ◽  
Author(s):  
J. L. Nikolajsen ◽  
D. Dong ◽  
M. J. Goodwin
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Damping Capacity ◽  
Bearing Load ◽  
Bearing Stiffness

Preliminary measurements have been conducted to determine the effect of oil aeration on journal bearing performance. Oil aeration was observed to reduce the bearing load capacity and to increase the bearing stiffness. Also, the bearing damping capacity was improved significantly by oil aeration.

A Contribution to the Analysis of the Thermo-Hydrodynamic Lubrication of Porous Self-Lubricating Journal Bearings

2010 ◽  
Vol 297-301 ◽  
pp. 618-623 ◽  
Author(s):  
S. Boubendir ◽  
Salah Larbi ◽  
Rachid Bennacer
Keyword(s):  
Thermal Effects ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Governing Equations ◽  
Hydrodynamic Analysis ◽  
Result Show

In this work the influence of thermal effects on the performance of a finite porous journal bearing has been investigated using a thermo-hydrodynamic analysis. The Reynolds equation of thin viscous films is modified taking into account the oil leakage into the porous matrix, by applying Darcy’s law to determine the fluid flow in the porous media. The governing equations were solved numerically using the finite difference approach. Obtained result show a reduction in the performance of journal bearings when the thermal effects are accounted for and, this reduction is greater when the load capacity is significant.

scholarly journals Experiments on an Ultrastable Gas Journal Bearing

1967 ◽  
Vol 89 (4) ◽  
pp. 433-438 ◽  
Author(s):  
S. B. Malanoski
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Design Data ◽  
Attitude Angle ◽  
Angle Data ◽  
The Stability ◽  
Data Design ◽  
Gas Journal Bearing

Shallow grooving in a herringbone pattern has been proposed to enhance the stability of both gas and liquid-lubricated journal bearings. It has been shown theoretically that this possibility is particularly advantageous for unloaded journal bearings. This paper describes corroborating experiments. The experiments included the running of an unloaded bearing up to speeds of 60,000 rpm and the collection of steady-state load-displacement, attitude angle data at intermediate speeds up to and including 60,000 rpm. No sign of bearing whirl instability was detected. There was good correlation between theoretical and experimental data. Design data for the partially grooved journal bearing is included for future designs.

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