Performance of Starved Journal Bearings With Oil Ring Lubrication

1985 ◽  
Vol 107 (1) ◽  
pp. 23-31 ◽  
Author(s):  
H. Heshmat ◽  
O. Pinkus
Keyword(s):  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Fluid Film ◽  
Experimental Program ◽  
Power Losses ◽  
Maximum Temperatures

An experimental program documenting the performance of journal bearings for conditions ranging from full hydrodynamic lubrication to states of extreme lubricant starvation is described. The effects of an incomplete fluid film on the eccentricity locus, extent of film, average and maximum temperatures, flow, and power losses are given as a function of amount of lubricant available to the bearing. In particular, the performance of starved bearings with oil ring lubrication is experimentally correlated to enable the designer to predict not only oil delivery by the ring, but also the resultant performance of the bearing.

An analytical study of the fluid film force in finite-length journal bearings. Part I

2001 ◽  
Vol 13 (4) ◽  
pp. 329-340 ◽  
Author(s):  
V. D'Agostino ◽  
D. Guida ◽  
A. Ruggiero ◽  
A. Senatore
Keyword(s):  
Finite Length ◽  
Analytical Study ◽  
Journal Bearings ◽  
Fluid Film

Theoretical Condition for the Cxy=Cyx Relation in Fluid Film Journal Bearings

1989 ◽  
Vol 111 (3) ◽  
pp. 426-429 ◽  
Author(s):  
T. Kato ◽  
Y. Hori
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Fluid Film ◽  
Finite Width ◽  
Damping Coefficients ◽  
Dynamic Coefficients ◽  
Cross Terms ◽  
Linear Damping ◽  
Theoretical Condition

A computer program for calculating dynamic coefficients of journal bearings is necessary in designing fluid film journal bearings and an accuracy of the program is sometimes checked by the relation that the cross terms of linear damping coefficients of journal bearings are equal to each other, namely “Cxy = Cyx”. However, the condition for this relation has not been clear. This paper shows that the relation “Cxy = Cyx” holds in any type of finite width journal bearing when these are calculated under the following condition: (I) The governing Reynolds equation is linear in pressure or regarded as linear in numerical calculations; (II) Film thickness is given by h = c (1 + κcosθ); and (III) Boundary condition is homogeneous such as p=0 or dp/dn=0, where n denotes a normal to the boundary.

Heat Transfer and Thermal Elastic Deformation Analysis on the Piston/Cylinder Interface of Axial Piston Machines

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Matteo Pelosi ◽  
Monika Ivantysynova
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Elastic Deformation ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Fluid Film ◽  
Design Elements ◽  
Piston Cylinder ◽  
Viscous Shear ◽  
Axial Piston

The piston/cylinder interface of swash plate–type axial piston machines represents one of the most critical design elements for this type of pump and motor. Oscillating pressures and inertia forces acting on the piston lead to its micro-motion, which generates an oscillating fluid film with a dynamically changing pressure distribution. Operating under oscillating high load conditions, the fluid film between the piston and cylinder has simultaneously to bear the external load and to seal the high pressure regions of the machine. The fluid film interface physical behavior is characterized by an elasto-hydrodynamic lubrication regime. Additionally, the piston reciprocating motion causes fluid film viscous shear, which contributes to a significant heat generation. Therefore, to fully comprehend the piston/cylinder interface fluid film behavior, the influences of heat transfer to the solid boundaries and the consequent solid boundaries’ thermal elastic deformation cannot be neglected. In fact, the mechanical bodies’ complex temperature distribution represents the boundary for nonisothermal fluid film flow calculations. Furthermore, the solids-induced thermal elastic deformation directly affects the fluid film thickness. To analyze the piston/cylinder interface behavior, considering the fluid-structure interaction and thermal problems, the authors developed a fully coupled simulation model. The algorithm couples different numerical domains and techniques to consider all the described physical phenomena. In this paper, the authors present in detail the computational approach implemented to study the heat transfer and thermal elastic deformation phenomena. Simulation results for the piston/cylinder interface of an existing hydrostatic unit are discussed, considering different operating conditions and focusing on the influence of the thermal aspect. Model validation is provided, comparing fluid film boundary temperature distribution predictions with measurements taken on a special test bench.

Performance of Stern Tube Bearings under Different Lubrication and Operating Conditions

2009 ◽  
Author(s):  
Jan H. Andersen ◽  
Hiroyuki Sada ◽  
Seiji Yamajo
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Water Soluble ◽  
Analysis Tool ◽  
Test Rig ◽  
Experimental Performance ◽  
Shaft Alignment ◽  
Alignment Analysis

This paper presents the results of an investigation into the theoretical and experimental performance of oil lubricated journal bearings. DNV has developed a new calculation tool for the analysis of journal bearing performance as part of shaft alignment analysis. The results of the calculation tool have been compared to other research and analysis methods under static and dynamic conditions. In addition, white metal bearings were tested with decreasing Sommerfeld number until loss of hydrodynamic lubrication. The experiments were carried out in a bearing test rig and with three different lubricants, normal mineral oil, emulsifying oil, and water-soluble oil. The tests were done with increasing water content in the lubricant. Results from the test were compared with calculation using the DNV analysis tool.

Performance analysis of rough surface hybrid thrust bearing with elliptical dimples

2020 ◽  
pp. 135065012093198
Author(s):  
Vivek Kumar ◽  
Satish C Sharma
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Machining Process ◽  
Fluid Film ◽  
Textured Surface ◽  
Stiffness Coefficient ◽  
Load Carrying Capacity ◽  
Power Losses ◽  
Load Carrying ◽  
Film Stiffness

Surface roughness is inherent to all machining processes. Therefore, even a high precision machining process renders micro-roughness to some extent on the surface of conventional materials. The asperities height of many rough engineering surfaces follows Gaussian distribution. The surface roughness on the bearing surface may significantly affect the bearing performance. Surface texturing is emerging as a new technique to improve the tribological behavior of the mating surfaces. Usually dimensions/height of micro-roughness is of order of the depth of surface textures in fluid film bearings. Neglecting micro-roughness while numerically simulating a textured surface bearing may generate inaccurate bearing performance data. In presented work, finite element simulation of textured surface hybrid thrust bearings has been performed. Surface texture is provided over thrust pad in the form of regular arrays of elliptical dimples. A parametric optimization is carried out to determine optimum attributes of elliptical dimple (axis, depth, texture length and orientation) so that the load-carrying capacity and fluid film stiffness should be maximized and film frictional power losses should be minimized. Use of textured surface (with optimum elliptical dimple attributes) results into a significant enhancement in load-carrying capacity (91.3%), film stiffness coefficient (+98.8%) and reduction in frictional power losses (−48.3%). It is also observed that elliptical dimple and micro-roughness (transverse orientation) generate synergistic effects in further enhancing the load-carrying capacity (+101.4%) and film stiffness coefficient (+112%) of the bearing.

scholarly journals Theoretical and Experimental Investigations on Transient Run-Up Procedures of Journal Bearings Including Mixed Friction Conditions

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 105 ◽  
Author(s):  
Maximilian Prölß ◽  
Hubert Schwarze ◽  
Thomas Hagemann ◽  
Philipp Zemella ◽  
Philipp Winking
Keyword(s):  
Experimental Data ◽  
Energy Equation ◽  
Hydrodynamic Lubrication ◽  
Frictional Coefficient ◽  
Journal Bearings ◽  
Numerical Code ◽  
Experimental Investigations ◽  
Lubrication Regime ◽  
Mixed Friction ◽  
Run Up

This paper focuses on the operating behavior of journal bearings for industrial machinery application during run-ups. For this purpose, a numerical simulation code that is based on a two-dimensional extended and generalized Reynolds equation and a full three-dimensional energy equation, was advanced by a theoretical model considering the effects of mixed friction and warming of journal components during start-up. The mixed friction routine contained the elastic half-spaces model proposed by Boussinesq, which considers the influence of rough surfaces by implementing flow factors and calculates additional stiffness and dissipation in areas with solid interactions. Furthermore, a transient term was added in the energy equation to consider the thermal inertia of journal, and bearing to ensure a realistic heating during run-ups. Results of the prediction were compared to experimental data taken from a special test rig built up for validation procedures. Besides the conventional sensors for temperature, oil flow, and relative motion between shaft and stator, a contact voltage measurement was installed to determine the intensity of mixed friction. The evaluation of experimental data by Stribeck curves, based on a shaft torsion measurement, indicated a significant influence of run-up time on frictional moment. The friction coefficient of the rotor bearing system was strongly influenced by the run-up time. A short run-up time reduced the frictional coefficient in the mixed lubrication regime while the opposite behavior was observed in the hydrodynamic lubrication regime. The numerical code predicted these tendencies in good agreement with experimental data, however, only if the transient energy model was applied.

A Contact-Wear Model for the EHL Analysis of Engine Journal Bearings

2005 ◽  
Author(s):  
Ducai Wang
Keyword(s):  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Surface Profile ◽  
Journal Bearings ◽  
Bearing Surface ◽  
Wear Model ◽  
Contact Wear ◽  
Analysis Technique ◽  
Elastic Distortion ◽  
Account Interaction

Engine journal bearings are now routinely analysed using elasto-hydrodynamic lubrication (EHL) methods [1,2]. This analysis technique takes into account interaction of the hydrodynamic film with the elastic distortion produced in both the bearing and the journal. It has proved a robust analytic tool for designers in predicting the value and location of such parameters as minimum oil film thickness and maximum film pressure. However, for some very heavily loaded cases, the normal EHL analysis technique may fail to produce realistic solutions. Due to ‘cusping’ of the bearing surface under extreme pressures the edges of bearing may be predicted to penetrate the journal surface leading to a ‘negative’ film thickness. In reality, the surfaces will interact and a ‘running-in’ process will result in subtle changes to the bearing surface profile such that a hydrodynamic film can be maintained across the whole bearing surface. This study introduces a contact-wear model which attempts to model this situation.

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