scholarly journals THE COMBINED EFFECT OF MAGNETIC FLUIDS WITH COUPLE STRESSES, VARIABLE VISCOSITY AND VELOCITY-SLIP ON THE LUBRICATION OF FINITE JOURNAL BEARINGS

2020 ◽  
Author(s):  
Tyrone Dass ◽  
Sreedhara Rao Gunakala ◽  
Donna Comissiong
Keyword(s):  
Journal Bearing ◽  
Slip Surface ◽  
Variable Viscosity ◽  
Frictional Coefficient ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Combined Effect ◽  
Viscosity Parameter ◽  
Load Carrying ◽  
Lubrication Characteristics

In this paper, we examine the combined effect of a non-Newtonian couple-stress lubricant, and a magnetic fluid, together with velocity-slip and piezo-viscosity, has on the lubrication characteristics of a finite journal bearing. Using the Stokes micro-continuum theorem and the Barus formula with an artificial (homogeneous) slip surface, we investigate the load-carrying ability, pressure distribution, and frictional coefficient of the bearing. Our results indicate that the piezo-viscosity parameter improves the maximum magnetic and hydrodynamic pressures of the journal bearing. The combined effect also significantly enhances the bearing characteristics.

scholarly journals Mixed and Fluid Film Lubrication Characteristics of Worn Journal Bearings

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Toshiharu Kazama ◽  
Yukihito Narita
Keyword(s):  
Frictional Coefficient ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Fluid Film ◽  
Asperity Contact ◽  
Lubrication Regimes ◽  
Lubrication Characteristics ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The mixed and fluid film lubrication characteristics of plain journal bearings with shape changed by wear are numerically examined. A mixed lubrication model that employs both of the asperity-contact mechanism proposed by Greenwood and Williamson and the average flow model proposed by Patir and Cheng includes the effects of adsorbed film and elastic deformation is applied. Considering roughness interaction, the effects of the dent depth and operating conditions on the loci of the journal center, the asperity-contact and hydrodynamic fluid pressures, friction, and leakage are discussed. The following conclusions are drawn. In the mixed lubrication regime, the dent of the bearing noticeably influences the contact and fluid pressures. For smaller dents, the contact pressure and frictional coefficient reduce. In mixed and fluid film lubrication regimes, the pressure and coefficient increase for larger dents. Furthermore, as the dent increases and the Sommerfeld number decreases, the flow rate continuously increases.

Controlling Journal Bearing Instability Using Active Magnetic Bearings

2007 ◽  
Author(s):  
A. El-Shafei ◽  
A. S. Dimitri
Keyword(s):  
Journal Bearing ◽  
Magnetic Bearing ◽  
Journal Bearings ◽  
Active Magnetic Bearing ◽  
Rotating Speed ◽  
Damping Characteristics ◽  
Oil Whip ◽  
Novel Approach ◽  
Oil Whirl ◽  
Load Carrying

Journal Bearings are excellent bearings due to their large load carrying capacity and favorable damping characteristics. However, Journal bearings are known to be prone to instabilities. The oil whirl and oil whip instabilities limit the rotor maximum rotating speed. In this paper, a novel approach is used to control the Journal bearing (JB) instability. An Active Magnetic Bearing (AMB) is used to overcome the JB instability and to increase its range of operation. The concept is quite simple: rather than using the AMB as a load carrying element, the AMB is used as a controller only, resulting in a much smaller and more efficient AMB. The load carrying is done by the Journal bearings, exploiting their excellent load carrying capabilities, and the JB instability is overcome with the AMB. This results in a combined AMB/JB that exploits the advantages of each device, and eliminates the deficiencies of each bearing. Different controllers for the AMB to control the JB instability are examined and compared theoretically and numerically. The possibility of collocating the JB and the AMB is also examined. The results illustrate the effectiveness of the concept.

Partial Slip Texture Slider and Journal Bearing Lubricated With Newtonian Fluids: A Review

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
A. Senatore ◽  
T. V. V. L. N. Rao
Keyword(s):  
Coefficient Of Friction ◽  
Surface Texture ◽  
Journal Bearing ◽  
Slip Surface ◽  
Load Capacity ◽  
Journal Bearings ◽  
Newtonian Fluids ◽  
Performance Characteristics ◽  
Partial Slip ◽  
Texture Properties

Partial slip texture surfaces have proven to be effective to improve load capacity and reduce coefficient of friction in slider and journal bearings. By controlling the partial slip surface texture properties, bearing with desired performance can be designed. It is of consequent interest to study the lubrication of slider and journal bearing systems taking into consideration design of partial slip texture surfaces. This paper aims at covering several investigation works related to slider and journal bearing lubricated with Newtonian fluids focusing on partial slip texture influence on bearing performance characteristics.

Designing the Partially Porous Journal Bearings of an Aerostatic Spindle

2017 ◽  
Vol 868 ◽  
pp. 110-117
Author(s):  
Te Yen Huang ◽  
Song Chiang Shen ◽  
Shao Yu Hsu
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Low Cost ◽  
Journal Bearings ◽  
Porous Insert ◽  
Load Carrying ◽  
High Speed Rotation ◽  
Ultra Precision ◽  
Precision Machine Tools ◽  
Aerostatic Spindle

The aerostatic journal bearings are widely used in ultra-precision machine tools. Due to remarkable ability of the porous medium in flow restriction, the porous aerostatic journal bearings are better than other types of aerostatic bearings in load carrying capacity, stiffness, damping and dynamic stability. The partially porous aerostatic journal bearing has the advantages of easy production and low cost. Moreover, the gap between the porous insert and the spindle can be adjusted to reduce the eccentricity due to high speed rotation. In this study, the effects of the size of the porous insert and the thickness of the air gap between the spindle and the housing on the gap pressure, the stiffness and the load carrying capability of the partially porous aerostatic journal bearing were figured out for performance evaluation.

Identification of dynamic coefficients of the journal bearing considering velocity slip of cavitation zone in the rotating spindle unit

2018 ◽  
Vol 232 (10) ◽  
pp. 1304-1317
Author(s):  
Feng Cheng ◽  
Weixi Ji
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Identification Accuracy ◽  
Identification Algorithm ◽  
Dynamic Coefficients ◽  
Displacement Error ◽  
Spindle Unit ◽  
Cavitation Erosion Resistance

A rotating spindle unit, supported by the journal bearings, is developed to improve the cavitation erosion resistance of the journal bearing as well as the spindle dynamic performance. The turbulent lubrication model considering velocity slip in cavitation zone is derived, and the static and dynamic parameters of the journal bearing are obtained. An identification algorithm is further derivated to identify simultaneously the 16 dynamic coefficients of the two journal bearings in the spindle unit. The available experimental results reveal that the journal bearing coefficients are well predicted and estimated by the present model, and the estimated bearing parameters by regularization solution are in good agreement with the assumed values, while it has opposite effect by directed solution for discrete ill-posed problems. It is concluded that the identification accuracy of bearing parameters is governed by the displacement error, and the percentage deviation of dynamic coefficients decreases with the decrease of the displacement error.

Optimal design of the slip–texture on a journal-bearing surface

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jian Jin ◽  
Xiaochao Chen ◽  
Yiyang Fu ◽  
Yinhui Chang
Keyword(s):  
Journal Bearing ◽  
Slip Surface ◽  
Interfacial Shear Stress ◽  
Journal Bearings ◽  
Combined Effects ◽  
Boundary Slip ◽  
Programming Technique ◽  
Content Type ◽  
Slip Regime ◽  
Lubrication Performance

Purpose This work aims to explore the combined effects of boundary slip and texturing on hydrodynamic journal bearings and identifies optimized slip and texture patterns to improve the performance of journal bearings. Design/methodology/approach The quadratic programming technique is used to study the influence of boundary slip on the lubrication performance of a two-dimensional journal bearing. A numerical model is used to analyze the effect of the cylindrical texture shape on the characteristics of journal bearings. It is concluded that the combination of slip and texture can be an effective approach to improve the performance of hydrodynamic journal bearings. Findings The results show that there is an interfacial shear stress (perfect slip surface) and that the role of the slip regime is to reduce friction. Numerical analyses indicate that the location and size of the slip and texture zone have a large effect on journal bearings. A comparison of the distribution forms of various texture–slip combinations indicates that the full texture–slip combination can prominently reduce the load-carrying capacity and that the “forward-slip backward-texture” configuration can considerably improve the performance of journal bearings. Originality/value The combined effects of boundary slip and texture on hydrodynamic journal bearings are meticulously examined. The patterns of the slip and texture are optimized, which can substantially improve the journal bearing performance.

scholarly journals Study on the performance of journal bearings in different lubricants by CFD and FSI method with thermal effect and cavitation

2018 ◽  
Vol 249 ◽  
pp. 03006 ◽  
Author(s):  
Hulin Li ◽  
Yanzhen Wang ◽  
Ning Zhong ◽  
Yonghong Chen ◽  
Zhongwei Yin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thermal Effect ◽  
Journal Bearing ◽  
Fluid Structure Interaction ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Load Carrying

This paper used a new transient computational fluid dynamics and fluid–structure interaction method to investigate the journal bearing performance with the effect of thermal and cavitation, to reveal the performance of journal bearing in different lubricants and to provide substitution references for bearings in different lubricants. Considering thermal effect, elastic deformation and cavitation, a detailed discussion was conducted to show the performance of plain journal bearings lubricated by water, seawater, and lubricating oil by computational fluid dynamics (CFD) and fluid structure interaction (FSI) method. And the results in this work are compared with the published results. The variation of dimensionless load carrying capacity, maximum film pressure and temperature with eccentricity ratio are presented, which can provide reference for the design of bearings. Furthermore, a diagram is presented for journal bearings with different diameter, length-diameter ratio and lubricants, which can be used as a reference for the equivalent substitutions of bearings. The present research provides references as to the design of bearings and the substitutions of bearings by different lubricants.

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