Analytical and Experimental Study of Externally Pressurized Air Lubricated Journal Bearings

1962 ◽  
Vol 84 (1) ◽  
pp. 159-165 ◽  
Author(s):  
Jason R. Lemon
Keyword(s):  
Journal Bearing ◽  
Design Parameters ◽  
Radial Clearance ◽  
Proper Selection ◽  
One Dimensional ◽  
Supply Pressure ◽  
Bearing Stiffness ◽  
Bearing Design ◽  
Gas Journal Bearing ◽  
Selection Of

A simplified analysis for calculating the characteristics, such as stiffness, flow, and load of an externally pressurized gas journal bearing, is obtained through a standard one-dimensional flow approach altered to take into account the effect of circumferential pressure variations. From this analysis, it is revealed that bearing stiffness has an optimum which, it is further shown, can be chosen through a proper selection of bearing design parameters, such as radial clearance, upstream resistor, and supply pressure. As the analysis is developed each assumption is experimentally verified. The final predictions of the analysis are also verified. It is felt that the analysis is sufficiently simple to allow comparison of many different bearing configurations, while sufficiently complete to compare very well against experimental measurements in all respects. A comparison is made between the recessed and nonrecessed bearing.

On the Optimization of the Stiffness of Externally Pressurized Bearings

1962 ◽  
Vol 84 (1) ◽  
pp. 119-122 ◽  
Author(s):  
Marvin T. S. Ling
Keyword(s):  
Optimum Condition ◽  
Film Thickness ◽  
Incompressible Fluid ◽  
Compressible Fluid ◽  
Theoretical Studies ◽  
Proper Selection ◽  
Supply Pressure ◽  
Bearing Stiffness ◽  
Selection Of

This paper presents theoretical studies of the method of optimization of the stiffness of externally pressurized bearings. When an externally pressurized bearing is designed to operate at any given film thickness, it is found that the maximum bearing stiffness can be obtained by proper selection of the value of the ratio of recess to supply pressure, Pr/Ps. While various values of Pr/Ps can be attained by either varying the restrictor constant for a given film thickness or varying the film thickness for a given restrictor constant, the important quantity to vary in determining the optimum condition is the restrictor constant rather than the film thickness. For an incompressible fluid, the Pr/Ps value for which the bearing stiffness is optimized depends only on the type of compensation used, while for a compressible fluid it is slightly affected by exhaust pressure.

Analysis of Externally Pressurized Gas Journal Bearing

1970 ◽  
Vol 12 (1) ◽  
pp. 1-8 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Numerical Method ◽  
Approximate Method ◽  
Journal Bearing ◽  
Design Parameters ◽  
Method Of Solution ◽  
Bearing Design ◽  
Numerical Method Of Solution ◽  
Gas Journal Bearing

An externally pressurized gas journal bearing with multiple supply holes is analysed theoretically by numerical method of solution. The load and flow are predicted by considering both axial and circumferential flow. These load and flow expressed in dimensionless factors are presented for different bearing design parameters. The results are compared with the similar available approximate method.

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.

Optimization of Clearance in a Squeeze-Film Journal Bearing

1971 ◽  
Vol 93 (2) ◽  
pp. 246-251
Author(s):  
C. L. Strodtman
Keyword(s):  
Numerical Methods ◽  
Small Parameter ◽  
Shape Factor ◽  
Journal Bearing ◽  
Diameter Ratio ◽  
Parameter Analysis ◽  
Squeeze Film ◽  
Clearance Ratio ◽  
Proper Selection ◽  
Selection Of

It is shown that a squeeze-film journal bearing supporting a mass completely contained within the bearing can be designed with the optimum value of minimum clearance by proper selection of the drive amplitude to nominal clearance ratio, the length to diameter ratio, and the shape factor of the excursion. Both a small parameter and an augmented, small parameter analysis are given. In the latter case, numerical methods are employed to solve the resulting equations. The results of the analysis are illustrated in application to an accelerometer design.

Analysis of Thermo-Active Foundations With U-Tube Heat Exchangers

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Khaled Rouissi ◽  
Moncef Krarti ◽  
John S. McCartney
Keyword(s):  
Numerical Approach ◽  
Heat Fluxes ◽  
Design Parameters ◽  
Transfer Model ◽  
Proper Selection ◽  
Unsteady Temperature ◽  
Heating And Cooling ◽  
Fluid Flow Velocity ◽  
Drilled Shaft Foundations ◽  
Selection Of

This paper presents a heat transfer model for thermo-active drilled-shaft foundations used for heating and cooling buildings. Specifically, this paper presents a numerical approach to evaluate the unsteady temperature distribution within the ground medium surrounding the foundation as well as indoor/outdoor heat fluxes. In particular, a 2D numerical solution was obtained using the finite difference technique with a purely implicit solution scheme. The results of the sensitivity analysis indicate that the efficiency of the thermo-active foundation can be significantly improved with a proper selection of design parameters including heat exchanger fluid flow velocity, foundation depth, and foundation materials.

Multiple Design Objectives in Hydrodynamic Journal Bearing Optimization

1984 ◽  
Vol 106 (1) ◽  
pp. 54-60 ◽  
Author(s):  
S. M. Metwalli ◽  
G. S. A. Shawki ◽  
M. O. A. Mokhtar ◽  
M. A. A. Seif
Keyword(s):  
Journal Bearing ◽  
Design Procedure ◽  
Oil Viscosity ◽  
Novel Approach ◽  
Design Variables ◽  
Loss Maximum ◽  
Hydrodynamic Journal Bearing ◽  
Bearing Design ◽  
Maximum Minimum ◽  
Selection Of

A novel approach is presented to optimize the finite journal bearing performance under steady loading conditions. Closed form expressions representing the behavior of the bearing as explicit functions of the design variables are utilized. Different competing objectives are assumed to suit various design applications. A method of multiplying objectives and raising to different exponents has been adopted. The basic competing objectives are minimum power loss, maximum-minimum film thickness, minimum side leakage, minimum temperature rise, and minimum bearing size. A journal bearing design procedure for optimum performance is thus devised for the selection of optimum bearing length, clearance, and oil viscosity. A numerical example is also presented.

Theoretical Analysis of Externally Pressurized Air Journal Bearing

1970 ◽  
Vol 12 (2) ◽  
pp. 123-129 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Experimental Data ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Dimensional Parameters ◽  
Bearing Design

A theoretical investigation is made to predict the performance of an externally pressurized air journal bearing having several pressure sources. The pressure distribution, which leads to the determination of load-carrying capacity and flow requirement, is obtained by solving Reynolds equation numerically. The load and flow, expressed in non-dimensional parameters, are presented for different bearing design parameters (dimensionless). The results predicted by this method are compared with others' experimental data.

Effects of Bearing Stiffness Anisotropy on Hydrostatic Micro Gas Journal Bearing Dynamic Behavior

2005 ◽  
Author(s):  
L. X. Liu ◽  
Z. S. Spakovszky
Keyword(s):  
Numerical Simulations ◽  
Dynamic Behavior ◽  
High Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Stiffness Anisotropy ◽  
Bearing Stiffness ◽  
Gas Bearing ◽  
Gas Journal Bearing ◽  
Fabrication Tolerance

The high-speed micro hydrostatic gas journal bearings used in the high-power density MIT micro-engines are of very low aspect ratio with an L/D of less than 0.1 and are running at surface speeds of order 500 m/s. These ultra-short high-speed bearings exhibit whirl instability limits and a dynamic behavior much different from conventional hydrostatic gas bearings. The design space for stable high-speed operation is confined to a narrow region and involves singular behavior (Spakovszky and Liu (2003)). This together with the limits on achievable fabrication tolerance that can be achieved in the silicon chip manufacturing technology severely affects bearing operability and limits the maximum achievable speeds of the micro turbomachinery. This paper introduces a novel variation of the axial-flow hydrostatic micro-gas journal bearing concept which yields anisotropy in bearing stiffness. By departing from axial symmetry and introducing biaxial symmetry in hydrostatic stiffness, the bearing’s top speed is increased and fabrication tolerance requirements are substantially relieved making more feasible extended stable high-speed bearing operation. The objectives of this work are: (1) to characterize the underlying physical mechanisms and the dynamic behavior of this novel bearing concept, and (2) to report on the design, implementation and test of this new micro-bearing technology. The technical approach involves the combination of numerical simulations, experiment, and simple, first principles based modeling of the gas bearing flow field and the rotordynamics. A simple description of the whirl instability threshold with stiffness anisotropy is derived explaining the instability mechanisms and linking the governing parameters to the whirl ratio and stability limit. An existing analytical hydrostatic gas bearing model is extended and modified to guide the bearing design with stiffness anisotropy. Numerical simulations of the full non-linear governing equations are conducted to validate the theory and the novel bearing concept. Experimental results obtained from a micro-bearing test device are presented and show good agreement between the theory and the measurements. The theoretical increase in achievable bearing top speed and the relief in fabrication tolerance requirements due to stiffness anisotropy are quantified and important design implications and guidelines for micro gas journal bearings are discussed.

Study on Dynamic Characteristics of a Hydrostatic and Hydrodynamic Journal Bearings for Small Diameter Grinding Spindle

2012 ◽  
Vol 497 ◽  
pp. 99-104 ◽  
Author(s):  
Zhi Quan Hou ◽  
Wan Li Xiong ◽  
Xue Bing Yang ◽  
Ju Long Yuan
Keyword(s):  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Small Diameter ◽  
Diameter Ratio ◽  
Design Parameters ◽  
Eccentricity Ratio ◽  
Dynamic Coefficients ◽  
Supply Pressure ◽  
Stiffness Coefficients ◽  
Direct Stiffness

The dynamic characteristics of a hydrostatic and hydrodynamic journal bearing with two arrays of eight holes have been investigated theoretically by the three-dimensional Computational Fluid Dynamics (CFD) models with respect to equilibrium position. The various dynamic coefficients for design parameters, such as orifice diameter, length to diameter ratio, eccentricity ratio, supply pressure, and rotational speed, are analyzed systematically under the action of displacement disturbance and velocity disturbance which are considered by the User Definition Function (UDF) programs. Results show that the dynamic coefficients greatly affected by design parameters. The cross stiffness coefficients increase rapidly more than direct stiffness with an increase of length to diameter ratio and rotational speed. Conversely, the direct stiffness coefficients are larger than cross stiffness with an increase of supply pressure and eccentricity ratio. It indicates that the journal bearing with two arrays of eight holes is suitable for their applications to small diameter grinding spindle by the means of optimizing the operating parameters and the structural parameters in order to obtain a better dynamic characteristic.

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