Performance Of Journal Bearing Research Articles

Experimental study on hydro- thermal behavior of journal bearing oil film profile in a slow speed diesel engine

Utilizing universal journal bearing test rig, the performance of a heavy-loaded main journal bearing has been investigated based on tracing operational behavior of oil film temperature and pressure profiles. Test trials were conducted observing the loading program of slow speed diesel engine. Examining the effect of different oil grades, it turned out that oil grade of higher viscosity index enhances journal bearing performance and maintains oil film temperature profile stability at both maximum speeds and heavy loads. Further, medium viscosity grade oil reduces fuel consumption and costs from power production for all operational conditions. Regarding the impact of heavy loads on shaft power performance with medium viscosity oil grade, the differences between optimal and heavy loads get lower as the shaft speed increases. Those were 22 %, 9.7 % and 2.1 % corresponding to the shaft speeds of 43 rpm, 90 rpm and 104 rpm respectively. Additionally, the lower the value of the maximum oil film pressure Pmax difference between optimal and heavy load, the higher the ability of the lubricant to promote performance and provide enhanced operating condition stability. Yet, at part load operating conditions entailing running journal shaft at slow speeds during ship maneuverability, it cannot be considered as the best selection due to the heavy loads often applied in such critical operating conditions. Finally, the test-trial based experimental outcomes can provide useful guidance regarding the proper selection of a lubricant for enhanced performance, cost saving and prolonged journal bearing working life.

Effect of rectangular rough dimples of textured surface on tribological behavior of a hydrodynamic journal bearing

The geometry and location of the textures can affect the hydrodynamic bearing and coefficient of friction for the journal bearing case. The present study deals with the analysis of the effect of texture containing dimples in rectangular forms with the introduction of micro-dimples at the same time (considered as roughness). The relationship between texture (dimples) and micro-texture (micro-dimples) is based on two key geometric parameters (roughness ratio and micro-dimples ratio). Numerical modeling is used to analyze the effect of rectangular texture, its geometry (with variation of these ratios) and its location on the tribological behavior in steady-state régime. The results indicate that a rectangular texture with roughness (micro-dimples) can considerably improve the performance of journal bearing.

Analysis of the Turbulent Lubrication of a Textured Hydrodynamic Journal Bearing

In order to investigate the turbulent lubrication performance of a textured hydrodynamic journal bearing (THJB), a model of turbulent lubrication was established in this paper. The variations in the Reynolds number, oil film thickness, oil film pressure, bearing capacity, attitude angle, and side leakage flow with structural and working parameters were studied, and the axis whirl orbit was further analyzed. The results show that turbulent lubrication is suitable for the actual operating conditions of THJBs. The Reynolds number decreases with the eccentricity ratio in the pressure-bearing zone but increases with rotational speeds, whereas the variation in the maximum oil film pressure increases and the minimum oil film thickness decreases with the eccentricity ratio under various Reynolds numbers. The bearing capacity decreases with the dimple diameter, depth, oil film thickness, and clearance ratio but increases with the length/diameter ratio and dimple spacing. As the eccentricity ratio increases, the attitude angle decreases, but the side leakage flow increases. In addition, the system tends to be unstable as the rotational speed and length/diameter ratio increase, and the friction and wear on the surface are three-body friction. This work not only helps in analyzing the characteristics of a THJB under actual operating conditions but also provides support for research on the simulation of THJB’s lubrication mechanism of THJB via computational fluid dynamics.

Numerical analysis of finite bearing operating under non-Newtonian lubricant and flow turbulence effect

The purpose of this work is to evaluate the combined influence of turbulence and shear-thinning/shear-thickening lubricant on the steady-state characteristics of hydrodynamic journal bearings. The modified Navier–Stokes equation for linear turbulence and non-Newtonian (shear-thinning as well as shear-thickening aspect) lubricants are solved using a finite element method to acquire load capacity, attitude angle, friction coefficient variable, total oil flow, and temperature rise variable for distinct combined values of the flow behavior index and Reynolds number. This work utilizes the Navier–Stokes equation with Ng–Pan's linear turbulence and shear-thinning/shear-thickening lubricant models, which is very helpful in predicting the performance characteristics of hydrodynamic bearings under harsh industrial operating conditions. The results show that the combined presence of non-Newtonian lubricant and turbulence in the flow significantly affects the steady-state performance parameters of such type of bearing compared to existence of individual presence of turbulence and non-Newtonian lubricant in the clearance space. This work helped to provide better insight into the operation of journal bearings in a severe environment owing to the high speed and changes in the nature of lubricant.

Experimental investigations on the friction behavior of partially femtosecond laser-textured journal bearing shells

Journal bearings are the most commonly used load elements in rotating systems and have a long history in tribology research. However, the relatively new surface modification technique of femtosecond laser texturing has rarely been used to increase the efficiency of journal bearings. We used a 300-fs laser to create chevron-shaped microstructures in different circumferential texture locations on half-bearing shells to investigate the effect of partial texturing on the tribological performance of journal bearings. With a customized shaft-bearing shell setup, the coefficient of friction and lubrication film thickness was tracked in two load scenarios at varying rotational speeds. In fully film conditions, the findings demonstrate that textures in the high-load region of journal bearings provide the highest lubricant film thickness and lowest friction compared to textures in the pressure build-up, divergent zone, and unstructured reference. Moreover, surface textures in the high-load area also perform better in boundary and mixed lubrication. Experimental data have also shown that asymmetric texture designs have a detrimental effect on lubrication performance. In contrast to symmetric designs, the lubrication film build-up is hindered. The research results represent a step toward transferring laboratory findings on laser surface texturing for tribological optimization in real applications.

Transient tribo-dynamic performance of journal bearings considering wear behavior during start-up

The transient tribo-dynamics and wear model are coupled to study the mixed lubrication-wear behavior during start-up. The coupled numerical model involves the film thickness equation with wear depth and a time-varying wear coefficient to account for the impact of transient mixed lubrication behavior on wear. In this study, the evolution of wear and mixed lubrication performance distribution over time is predicted, and the impact of acceleration mode, acceleration time, external load, lubricant viscosity, and start-up time on the numerical predictions is evaluated. The findings demonstrate that wear behavior, particularly in the analysis of the effects of acceleration mode and acceleration time, has a significant impact on the evaluation of the bearing-rotor system's start-up performance and even changes the determination of optimal parameters. Furthermore, the parametric study demonstrates that wear and mixed lubrication performance are sensitive to the external load and lubricant viscosity. Finally, studies on the effect of start-up times show that proper wear geometry promotes hydrodynamic effects, but severely worn bearing surfaces have a negative effect on start-up.

Experimental Investigation of Main Journal Bearing Performance in Marine Applications with Heavy Loads at Slow Speeds Utilizing Different Grade Oils

Heavy loads are known to be among the most critical operational factors affecting the behavior of the lubricating oil film within journal bearing related to marine slow speed diesel engines. In light of the fact, a comprehensive investigation was carried out to examine the performance of journal bearing under heavy loads resulting from increased maximum pressure within the combustion chamber. Further, the research test trial procedures have been extended to cover the different speed ranges of 40 rpm, 85 rpm and 105 rpm, as corresponding to the engine loads (40 %, 85% and 100 % respectively), together with the different oil grades of 20W50, 5W40 and 0W30. Universal Journal Bearing Test Rig (UJBTR) was utilized for conducting the experimental test trials due to its capability to contain versatile variations regarding the key operational factors. Experimental test trials basically based on tracing the changes in the oil film pressure distribution and the maximum oil film pressure values, have given insight into the behavior of heavy-loaded journal bearing of diesel engine related to ships. Based all the experimental test trials under optimal and heavy load conditions, oil grade 5W40 was concluded to provide the most optimal operating conditions for all tested speed ranges.

Experimental Investigation of Main Journal Bearing Performance in Marine Applications with Heavy Loads at Slow Speeds Utilizing Different Grade Oils

Heavy loads are known to be among the most critical operational factors affecting the behavior of the lubricating oil film within journal bearing related to marine slow speed diesel engines. In light of the fact, a comprehensive investigation was carried out to examine the performance of journal bearing under heavy loads resulting from increased maximum pressure within the combustion chamber. Further, the research test trial procedures have been extended to cover the different speed ranges of 40 rpm, 85 rpm and 105 rpm, as corresponding to the engine loads (40 %, 85% and 100 % respectively), together with the different oil grades of 20W50, 5W40 and 0W30. Universal Journal Bearing Test Rig (UJBTR) was utilized for conducting the experimental test trials due to its capability to contain versatile variations regarding the key operational factors. Experimental test trials basically based on tracing the changes in the oil film pressure distribution and the maximum oil film pressure values, have given insight into the behavior of heavy-loaded journal bearing of diesel engine related to ships. Based all the experimental test trials under optimal and heavy load conditions, oil grade 5W40 was concluded to provide the most optimal operating conditions for all tested speed ranges. Keywords: Hydrodynamic Lubrication, Pressure Distribution, heavy loads, Slow Speeds, Oil Grades.

A New Type of Misaligned Journal Bearing with Flexible Structure

A flexible structure is applied to improve the lubrication performance of a misaligned journal bearing. The journal bearing is a representative sliding bearing, and there is damage due to metal-to-metal contact as a result of misalignment. Since misalignment is an unavoidable phenomenon, a journal bearing with a flexible structure was proposed as a way to improve it. The lubrication characteristics of the bearing were evaluated numerically under a steady-state condition. EHL (elastohydrodynamic lubrication) analysis considering elastic deformation was performed. The lubrication performance was compared in accordance with variation of the geometry of the flexible structure and evaluated based on the minimum film thickness. Moreover, the results of the journal bearing with a flexible structure were compared with those of the journal bearing without the flexible structure. The flexible structure was then applied in the form of a groove to the area supporting high load on the journal bearing; it was elastically deformed by the generated oil film pressure, which helps obscure a larger oil film. Through numerical analysis, it was found that the journal bearing with a flexible structure can improve the lubrication performance in the misaligned condition.

Performance of hydrodynamic textured journal bearing with the combined influence of elastic deformation and pseudo-plastic lubricant

This study outlines the performances of finite-length journal bearing with textured liner, shear-thinning Rabinowitsch lubricants, and considers the elastic deformation of the bearing liner. The yielded nonlinear Rabinowitsch-Reynolds PDE system has been solved using the finite difference method combined with Elrod’s algorithm for the case of cylindrical textures. The static performance of hydrodynamic lubrication, in this case, involves different parameters such as depth of texture, eccentricity ratio, elastic deformation factor, rheological index, etc. Results showed that, at a fixed eccentricity ratio, texturing of the bearing’s converging area enhances significantly the load-carrying capacity and reduces the friction coefficient compared to the smooth bearing surface (up to [Formula: see text] in load capacity and [Formula: see text] in friction coefficient). On the other hand, using a lubricant with more pronounced shear-thinning behavior and/or elastic liner reduces the journal bearing performances (up to [Formula: see text] in load capacity and [Formula: see text] in pressure). By applying the optimization technique (particle swarm optimization), an optimal arrangement of textures that can compensate for these losses in performance even at high eccentricity has been found. This optimal texture with dimensionless dimple’s depth set to 1 [Formula: see text] improves the load capacity with [Formula: see text] for a lubricant with a rheological index [Formula: see text] and elastic bearing liner with deformation parameter [Formula: see text].

A Fluid-Structure Interaction Method for the Elastohydrodynamic Lubrication Characteristics of Rubber-Plastic Double-Layer Water-Lubricated Journal Bearings

This paper proposes a fluid-structure interaction (FSI) numerical calculation method for investigation of the elastohydrodynamic lubrication performance of the rubber-plastic double-layer water-lubricated journal bearings. The accuracy and rapidity of the FSI method are improved by studying the effect of mesh density and by comparing the calculation results with those in the literature. Based on the proposed method, a series of numerical simulations are carried out to reveal the influence of operating conditions and structural parameters on the lubrication performance of the rubber-plastic bearings. Numerical results show that the bush deformation of the rubber-plastic bearing is between that of the rubber bearing and the plastic bearing, and the deformation area is close to that of the rubber bearing. The bearing load carrying capacity increases significantly with the rotational speed, eccentricity ratio, bearing length, and decrease with the clearance. But the influences of the plastic layer elastic modulus and thickness on bearing load are unremarkable. The effect of bush deformation on bearing load is noticeable when the eccentricity ratio is more than 0.8. The results are expected to provide design references for the bearings.

Stochastic Performance of Journal Bearing With Two-Layered Porous Bush—A Machine Learning Approach

Abstract This investigation presents the deterministic and stochastic responses of the journal bearing with a two-layered porous bush. Pressure equations in the porous layers and modified Reynolds equations in the clearance region are governed by the finite difference method (FDM). Stochastic analysis based on Monte Carlo simulation (MCS) is used to investigate the effect of random variation in input parameters caused by uncertain operating conditions, improper installations, and manufacturing imperfections. In order to enhance computational efficiency, this probabilistic study is conducted in conjunction with the machine learning (ML) model based on the support vector machine (SVM) algorithm. The uncertainty in the bearing responses is presented in the form of the probability density function (PDF), considering both the independent and combined effect of the stochastically varied input parameters. Graphical illustration of the data-driven sensitivity represents the relative significance of each input parameter affecting the steady-state responses of the journal bearing with two-layered porous bush. The findings of the present study reveal that the stochastic variations in the input parameters have a profound influence on the operational characteristics of the porous bearing. The outcome of the present study will be helpful in deciding the operational regime of the porous bearing under the practically relevant stochastic environment.

Thermo-hydrodynamic Analysis of Misaligned Journal Bearing Considering Surface Roughness and Non-Newtonian Effects

This paper presents a numerical simulation for the combined effect of surface roughness and non-Newtonian behavior of the lubricant on the performance of misaligned journal bearing. The modified Reynolds equation to include the effect of non-Newtonian lubricant and bearing surface roughness has been formulated. The model accounts for the lubricant viscosity dependence on temperature and shear rate. In order to make a complete thermo-hydrodynamic analysis (THD) of rough surface misaligned journal bearing lubricated with non-Newtonian lubricant, the modified Reynolds equation coupled with the energy, heat conduction equations, the equation related the viscosity and temperature with appropriate boundary conditions have been solved simultaneously. The performance characteristics of the bearing were presented with different roughness parameter for the pressure, temperature, load carrying capacity, misalignment moment and friction force. The computer program prepared to solve the governing equations of the problem has been verified by comparing the results obtained through this work with that published by different workers. It has been foundthat the results are in a good agreement .The results obtained in the present work showed that the surface roughness characteristics of opposing surfaces and its orientation play an important role in affecting the performance parameters of the bearing. It has been shown that the load in rough aligned journal bearing is higher than that in rough misaligned journal bearing for all surface roughness patterns (γ). An increase in load has been calculated and found to be 29.5% for the bearing with moving roughness while it becomes32% for the bearing with stationary roughness.

Analysis of Modified Finite Length Journal Bearing under Position Perturbation

The performance of journal bearings is significantly affected by the presence of misalignment, which is usually an accompanying problem for this type of bearing. This includes exceeding the design limits for the maximum pressure and the minimum film thickness levels, which affect, in other words, the load-carrying capacity of the system. In addition, it raises the possibility of increasing the wear rate at the bearing edges and increases the friction coefficient at high levels of misalignment. This paper deals with the problem of finite-length misaligned journal bearings, considering a novel comparison between two cases of misalignments: the general 3D misalignment and the vertical misalignment problems for modified bearings. The effect of introducing a variable axial bearing profile on the bearing characteristics and the time responses of the rotor bearing system under position perturbation has also been investigated. The numerical solution of this hydrodynamic problem is based on the finite difference method using Reynolds boundary conditions method. Results show that using a variable bearing profile improves bearing characteristics, such as increasing the minimum film thickness significantly and reducing the pressure levels in addition to reducing the friction coefficient. Furthermore, the modification enhances the rotor-bearing stability under position perturbation, extending the speed range for a safe operation.

Analysis of maximum radial load capacity of hydrostatic journal bearing considering supply pressure limitation by a novel method

The aim of the present study is the numerical analysis of the operating conditions (rotary speed, supply pressure) and structure parameters’ (capillary design parameter, recess wrap angle) influence on the performance of a four-rectangle recessed hydrostatic journal bearing, taking into account the limitation of the recess pressure that is always smaller than supply pressure. A new calculation method is proposed that ensures both lower time consumption than traditional numerical method (FEM, FDM) and higher accuracy than simplified method (Liang’s method). This approach examines the effect of operating conditions and structure parameters on the maximum load capacity, attitude angle, and maximum eccentricity ratio considering the supply pressure limitation. Moreover, the pressure distribution under various operating conditions and structure parameters is also investigated to explore their contributions to the performance of the hydrostatic journal bearing. The results indicate an excellent guiding significance for the design and application of hydrostatic journal bearings.

Numerical Study on the Bearing Capacity of Lubricant Film in Journal Bearing with Micro-textured Surface

For studying the hydrodynamic lubrication performance of micro-textured radial journal bearings, a numerical model of hydrodynamic lubrication for journal bearings was established first. Solve the established numerical model using FDM, and the lubricant film pressure distribution and static characteristics of bearings were obtained. Considering the processing cost and feasibility of the processing technology, the cylindrical texture arranged in the radial of the bearing shell surface is applied, the lubricant film thickness equation considering the micro-texture is introduced into the Reynolds equation. According to the height and distribution density of microstructure, the bearing capacity parameters were obtained. The load-carrying capacity of micro structure journal bearing is significantly higher than that of plain bearing. In this paper, a practical model with cylindrical micro-textured surface is given for journal bearing applications with high capacity demand.

Micropolar lubricant effects on the performance of partial journal bearings

Present work deals with the computation of static performance of partial journal bearing, operated with micropolar lubricant. The non-dimensional Reynolds equation governs the lubricant flow in clearance space and finite element method is used to solve it. Static characteristics including bearing load capacity, attitude angle, friction force, friction factor, and side flow are presented. Input parameters are chosen such as partial angles 120° and 180° and a width-diameter ratio (1.0), for a range of micropolar fluid parameters. The numerically simulated results show that the bearing geometry and lubricant micropolar parameters on higher side, provide an improved static performance of partial journal bearing system.

Effect of lubricant inertia on steady-state characteristics of textured hydrodynamic journal bearing

PurposeThis paper aims to investigate the effects of inertia of the lubricant on the performance parameters of journal bearings textured with spherical-shaped textures.Design/methodology/approachThe lubricant is assumed to be Newtonian, and the flow is considered laminar. Considering the lubricant inertia effects, the modified Reynolds equation is discretized using the finite difference method and solved with the Gauss–Seidel successive over-relaxation scheme using the progressive mesh densification method.FindingsThe results from this numerical study indicate that the lubricant inertia improves textured journal bearing performance characteristics significantly. The improvement is more significant in the case of heavily loaded bearings. Furthermore, it is observed that protruded texturing in journal bearings shows better results compared to dimple textured journal bearings.Originality/valueUnderstanding the effect of lubricant inertia is essential for efficiently designing textured journal bearings. Thus, the results shown here would be helpful for the researchers and the bearing designers.

Research on the influence of lubrication performance of hydrodynamic journal bearings based on orthogonal test method

The orthogonal experiment design method is used based on analysis of lubrication of hydrodynamic journal bearing．The effect of structural parameters ( bearing diameter，wide diameter ratio and clearance ratio) and operating parameters ( linear velocity and specific pressure) on lubrication performance of hydrodynamic journal bearings is studied． The results show that the linear velocity and specific pressure have significant influence on maximum oil film pressure of the bearings．The influence of specific pressure and bearing diameter on load capacity of the bearings is significant．The bearing diameter and linear velocity have significant influence on discharge flow of the bearings．The linear velocity has the most significant influence on friction power loss of the bearings when the low viscosity lubricant is used， and the clearance ratio，specific pressure and bearing diameter have a great influence on friction power loss of the bearings when the high viscosity lubricant is used．

Computational fluid dynamics study to investigate the performance of fluid film journal bearings with different geometries

The geometry of a hydrodynamic journal bearing plays a vital role in the rotating machinery. In this work, the performance characteristics of the plain and elliptical journal bearings are carried using Computational Fluid Dynamics (CFD) approach. An alternative approach to thermo-hydrodynamic analysis is presented assuming that all the heat that is generated by viscous shear in the fluid film is dissipated only in the fluid (no heat conduction through the boundaries). The effect of lubricant viscosity and bearing geometry on the pressure distribution is presented. The analysis is done for a wide range of speed (500–1000 rpm.) and lubricant viscosity at 1000 N load. In this paper, the theoretical results obtained are validated by computational methodology. The pressure distribution in the elliptical bearing is highly increased as compared to the plain bearing. The percentage increase upto 370.44 % is observed in the elliptical bearing. The Computational Fluid Dynamics (CFD) method can be very useful tool for study on the bearing lubrication problem and can accurately predict the performance characteristics of hydrodynamic journal bearing.