ANALYSIS OF HYDRODYNAMIC LUBRICATION OF JOURNAL BEARINGS WITH OIL OF NON-NEWTONIAN PROPERTIES

Tribologia ◽  
2018 ◽  
Vol 272 (2) ◽  
pp. 127-138
Author(s):  
Andrzej MISZCZAK ◽  
Grzegorz SIKORA
Keyword(s):  
Shear Rate ◽  
Carrying Capacity ◽  
Apparent Viscosity ◽  
Hydrodynamic Lubrication ◽  
Type Equation ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Third Order ◽  
The Third ◽  
Order Of Magnitude

In this paper, the presented issue concerns hydrodynamic lubrication of the journal bearings with the oil of non-Newtonian properties. For the analysis of the hydrodynamic lubrication, a constitutive model of the third order was assumed. The assumed model consist of a Newtonian part –pI+ηA1 and non-Newtonian part β3·tr(A1 2)A1. The main part of this paper concerns transformation, nondimensionalization, and an estimation of the order of magnitude of the equation, which describes the apparent viscosity. Apparent viscosity describes changes in the dynamic viscosity with shear rate. In this way, the prepared model of apparent viscosity is used in momentum equations. These equations are integrated in order to designate components of the velocity vector. By substitution of the proper boundary conditions, a modified Reynolds type equation is obtained. A further stage of the research will be proceeding of the numerical calculations of the hydrodynamic pressure distribution followed by the designation of the carrying capacity, friction force, and friction coefficient while taking changes of the viscosity from shear rate into account (apparent viscosity).

THE CHANGE OF FRICTION AND LOAD- CARRYING CAPACITY OF THE JOURNAL BEARING WITH THE CONSIDERATION OF THE OIL AGEING

Tribologia ◽  
2016 ◽  
Vol 269 (5) ◽  
pp. 171-181
Author(s):  
Grzegorz SIKORA ◽  
Andrzej MISZCZAK
Keyword(s):  
Shear Rate ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Load Carrying Capacity ◽  
Motor Oil ◽  
Temperature Influence ◽  
Load Carrying ◽  
Viscosity Changes

This paper presents numerical calculations of the hydrodynamic pressure distribution, carrying capacity, and friction coefficient in the gap of a journal bearing. The analysed bearing is lubricated using motor oil. In this paper, oil ageing and temperature influence on viscosity are taken into account. Viscosity changes in the pressure and shear rate are not considered. These changes will be considered in other papers. For the hydrodynamic lubrication analysis, laminar flow of the lubrication fluid and non-isothermal lubrication model of the journal bearing were assumed. As the constitutive equation, the classical, Newtonian model was used. This model was extended by the viscosity changes in temperature and exploitation time. For the considerations, the cylindrical journal bearing with the finite length and smooth bearing, with the full angle of wrap were taken.

scholarly journals On the modified Reynolds equation for journal bearings in a case of non-Newtonian Rabinowitsch fluid model

2018 ◽  
Vol 145 ◽  
pp. 03007
Author(s):  
Juliana Javorova ◽  
Jordanka Angelova
Keyword(s):  
Numerical Modeling ◽  
Constitutive Equation ◽  
Theoretical Analysis ◽  
Continuity Equation ◽  
Reynolds Equation ◽  
Fluid Model ◽  
Type Equation ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Dimensionless Equation

In this paper, a theoretical analysis of hydrodynamic plain journal bearings with finite length at taking into account the effect of non-Newtonian lubricants is presented. Based upon the Rabinowitsch fluid model (cubic stress constitutive equation) and by integrating the continuity equation across the film, the nonlinear modified 2D Reynolds type equation is derived in details so that to study the dilatant and pseudoplastic nature of the lubricant in comparison with Newtonian fluid. A dimensionless equation of hydrodynamic pressure distribution in a form appropriate for numerical modeling is also presented. Some particular cases of 1D applications can be recovered from the present derivation.

scholarly journals Bifurcation Analysis of Rotor/Bearing System using Third Order Journal Bearings Stiffness and Damping Coefficients

2021 ◽  
Author(s):  
Tamer Elsayed ◽  
Hussein Sayed
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Third Order ◽  
The Third ◽  
Bifurcation Stability ◽  
Jeffcott Rotor ◽  
Load Carrying ◽  
Proper Design ◽  
Rotor Stiffness ◽  
Stiffness And Damping

Abstract Journal bearings have many applications in industry due to its high load carrying capacity. In addition proper design of journal bearings enables safe operation at very high speeds. However, they are susceptible to oil whirl instability which may cause bearing failure. The fluid film pressure distribution inside the journal bearing is described by Reynolds equation. Many studies had been done to approximate the bearing performance using first order bearing coefficients. Although this analysis is stable for evaluating the threshold speed but it is insensitive to limit cycles above the threshold speed. Mush literature show that above the threshold speed, subcritical or supercritical bifurcations may be observed. Therefore, the aim of the present paper is to evaluate the third order bearing coefficients for a finite length journal bearing using finite perturbation method. The values of these coefficients are evaluated using infinitesimal perturbation analysis. These values are used to investigate the bifurcation stability of flexible Jeffcott rotor supported by two symmetric journal bearings. The effect of rotor stiffness ratio on the bifurcation stability of the system is investigated. The results of this work show that the third order parameters can be used to evaluate the type of bifurcation above the threshold speed.

scholarly journals Bifurcation analysis of rotor/bearing system using third-order journal bearing stiffness and damping coefficients

2021 ◽  
Author(s):  
T. A. El-Sayed ◽  
Hussein Sayed
Keyword(s):  
Equations Of Motion ◽  
Journal Bearings ◽  
Third Order ◽  
Damping Coefficients ◽  
The Third ◽  
Rotor Bearing ◽  
Bearing Stiffness ◽  
Rotor Stiffness ◽  
Stiffness And Damping ◽  
Bearing System

AbstractHydrodynamic journal bearings are used in many applications which involve high speeds and loads. However, they are susceptible to oil whirl instability, which may cause bearing failure. In this work, a flexible Jeffcott rotor supported by two identical journal bearings is used to investigate the stability and bifurcations of rotor bearing system. Since a closed form for the finite bearing forces is not exist, nonlinear bearing stiffness and damping coefficients are used to represent the bearing forces. The bearing forces are approximated to the third order using Taylor expansion, and infinitesimal perturbation method is used to evaluate the nonlinear bearing coefficients. The mesh sensitivity on the bearing coefficients is investigated. Then, the equations of motion based on bearing coefficients are used to investigate the dynamics and stability of the rotor-bearing system. The effect of rotor stiffness ratio and applied load on the Hopf bifurcation stability and limit cycle continuation of the system are investigated. The results of this work show that evaluating the bearing forces using Taylor’s expansion up to the third-order bearing coefficients can be used to profoundly investigate the rich dynamics of rotor-bearing systems.

scholarly journals Nanofluids for Performance Improvement of Heavy Machinery Journal Bearings: A Simulation Study

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2120 ◽  
Author(s):  
Hamid Sadabadi ◽  
Amir Sanati Nezhad
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Computational Simulation ◽  
Weight Fraction ◽  
Journal Bearings ◽  
Load Carrying Capacity ◽  
Inorganic Fullerene ◽  
Aggregation Effect ◽  
Load Carrying

Nanofluids have extensive applications in hydrodynamic journal bearings used in heavy industry machinery. Inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2 NPs) are the most common additive for lubrication purpose due to their excellent mechanical characteristics along with their effect on reducing friction and wear. In this work, a computational simulation approach with discrete phase modeling (DPM) of suspended nanoparticles was used to evaluate the application of the IF-WS2 nanofluid lubricant on load carrying capacity of high-load journal bearings where the normal loads are high, considering the bearing dimensions. For accurate simulation, nanofluid viscosity was calculated considering the aggregation effect of NPs by using scanning electron microscopy (SEM) imaging of the nanofluids. A benchmark study was first performed to assess the model accuracy. Hydrodynamic lubrication was simulated under different nanofluid weigh fractions. The simulated pressure distribution was then employed to determine the load capacity of the bearing. The results show an approximately 20% improvement of load carrying capacity at 5% weight fraction of WS2-oil nanofluid.

scholarly journals Application of the Optimization Methods to the Search of Marine Propulsion Shafting Global Equilibrium in Running Condition

2019 ◽  
Vol 26 (3) ◽  
pp. 172-180
Author(s):  
Aleksandr Ursolov ◽  
Yuriy Batrak ◽  
Wieslaw Tarelko
Keyword(s):  
Interior Point Method ◽  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Optimization Methods ◽  
Journal Bearings ◽  
Marine Propulsion ◽  
Minimum Film Thickness ◽  
Calculation Results ◽  
Global Equilibrium ◽  
Particle Swarm Method

Abstract Full-film hydrodynamic lubrication of marine propulsion shafting journal bearings in running condition is discussed. Considerable computational difficulties in non-linear determining the quasi-static equilibrium of the shafting are highlighted. To overcome this problem the approach using two optimization methods (the particle swarm method and the interior point method) in combination with the specially developed relaxation technique is proposed. The developed algorithm allows to calculate marine propulsion shafting bending with taking into account lubrication in all journal bearings and exact form of journal inside bearings, compared to results of most of the publications which consider lubrication only in the aft most stern tube bearing and assume rest of bearings to be represented by points. The calculation results of typical shafting design with four bearings are provided. The significance of taking into account lubrication in all bearings is shown, specifically more exact values of bearings’ reactions, shafting deflections, minimum film thickness and maximum hydrodynamic pressure in the stern tube bearing in case of considering lubrication in all bearings.

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