Hydrodynamic Journal Bearings Research Articles

Prediction and Optimization of a Hydrodynamic Journal Bearing’s Energy Efficient Tribological Behaviours for Different Grades of Lube Oil: A Novel DoE-RSM Strategy

Prediction and Optimization of a Hydrodynamic Journal Bearing’s Energy Efficient Tribological Behaviours for Different Grades of Lube Oil: A Novel DoE-RSM Strategy

Experimental and Numerical Analysis of Torsional—Lateral Vibrations in Drive Lines Supported by Hydrodynamic Journal Bearings

Experimental and Numerical Analysis of Torsional—Lateral Vibrations in Drive Lines Supported by Hydrodynamic Journal Bearings

Investigation of nanoparticle diameter influences on performance of hydrodynamic journal bearings operating with nanolubricant

The nanolubricant's effectiveness on the bearings’ performance depends on the types of nanoparticles, volume ratio, and their size and/or diameter. Although the nanolubricant influences on the characteristics of the journal bearings are well known, cost-effective solutions for using nanolubricants, have continued to need in industrial applications. Because the nanoparticle's diameter plays a key role in the fluid with nanoparticle additives, research on its effect is important for hydrodynamic journal bearing. In this work, the nanoparticle diameter impacts on the characteristics of the hydrodynamic journal bearings are investigated with under thermal effects. At first, four hydrodynamic journal bearings have different parameters such as radial clearance and bearing length–diameter ratio are considered and designed. Then, the lubricant flow through the radial clearance is modeled with Dowson's equation. Besides, the temperature field in the journal and the lubricant are governed by the heat conduction and energy equations, respectively. The physical and thermal properties of the nanolubricant are expressed by considering nanoparticle diameter and the volume ratio. Then, an algorithm is developed to solve the mathematical models based on the finite difference method. Finally, a serial simulation is conducted under different nanoparticle diameters and operational conditions. When the nanoparticle diameter becomes small, the temperature and pressure values of the nanolubricant, load capacity, and stiffness increase.

Mathematical Model and Theoretical Investigation of the Performance of Journal Bearing using a discretized Reynolds Lubrication Equation with Finite Width

Hydrodynamic journal bearings are widely used for a large number of applications such as rotating turbo machinery, axial flow compressors, axial flow turbines, and internal combustion engines. These types of journals are used to support high loads high speed rotating turbo machinery elements mainly shafts and attached components and also for enhancing the quality of these machines. In this work, the importance of journal bearing and an overview of the Reynolds hydrodynamic equation in three dimensions have been studied using the Boundary Value finite-difference method. The second-order nonlinear partial differential equation has been solved using numerical iterations approach with MATLAB software. The numerical solution of the transient Reynolds equation has been studied to investigate the Pressure distribution, pressure gradient as well film lubricant thickness on journal bearings. A numerical solution using ANSYS FLUENT has been applied to investigate the main parameters that have the main influence on the performance of the journal bearing and bearing performance.

A critical review of the effect of nano-lubricant on the performance of hydrodynamic journal bearing

The applications of nano-lubricants in journal bearing are found to be capable of improving load-carrying capacity and reducing friction. Many numerical and experimental investigations have been performed to find the effect of nano-lubricants on the performance of the journal bearing. In this paper, a state-of-the-art review is done of the articles of numerical and experimental assessments of the effect of nano-lubricants on the performance of journal bearings. Here research articles are classified on the basis of nanoparticles used as nano-additive, which are further classified in the category of numerical and experimental study. It is seen that the application of nano TiO2, CuO and Al2O3 based nano-lubricants gives much higher load-carrying capacity than the base lubricants. This article concludes by discussing the effect of different nanoparticle-based nano-lubricants on the performance characteristics of the journal bearing and mathematical models used for numerical investigations.

Effect of textured parameters on tribological properties of hydrodynamic journal bearing

PurposeThis study aims to improve the tribological properties of hydrodynamic journal bearing via surface texture, as well as the wear and antifriction mechanisms of textured bearing were represented. It provides a design direction for solving the tribological problem of rotor-bearing system.Design/methodology/approachIn this paper, the variation of surface texture parameters (e.g. texture diameter, d; area density, sp; and depth, hp) were analyzed based on finite difference method. The optimal surface texture parameters were obtained by designing orthogonal experiments, and the relationship between friction and wear properties and microstructure was studied via combining electron probe microanalyzer, scanning electron microscope, X-ray diffractometer and friction and wear testing machine.FindingsDimensionless film pressure P increased as the d increased, whereas P first increased and then decreased as the sp and hp increased, and the maximum P was got as sp = 15% and hp = 25 µm, respectively. The friction coefficient of textured surface with suitable parameters was effectively reduced and the textured surface with the best antifriction effect was 5#. Orthogonal experimental design analysis showed that the influence order of factors on friction coefficient was as follows: sp > sp × d > d > d × hp > hp > sp × hp and the friction coefficient first decreased and then increased as the sp, d and hp increased. In addition, the friction and wear mechanism of textured bearing were three body friction and abrasive wear as the matrix structure and hard phase were a single β phase and Mn5Si3, respectively. While the antifriction mechanism of textured surface was able to store abrasive particles and secondary hydrodynamic lubrication was formed.Originality/valueThe sample with reasonable texture parameter design can effectively reduce friction and wear of hydrodynamic journal bearing without reducing the service life, which can provide a reference for improving the lubrication performance and mechanical efficiency of rotor-bearing system.

A second-order in time and space model to solve the coupled Reynolds–Rayleigh–Plesset equations for the dynamics of cavitated hydrodynamic journal bearings

Cavitation in hydrodynamic bearings is a fundamental factor in the behavior of the fluid film and in the equilibrium position the journal will have after the application of external loads. The calculation of these parameters by robust tools is an active research topic even though accuracy, stability and conservativeness are not so often discussed. This work shows the results obtained through the implementation of a novel model developed from first principles that allows characterizing the pressure field of a liquid–gas lubricant mixture avoiding the reported instabilities with the time derivative of the mixture density. The formulation also relies on a coupled transport equation describing the evolution of the liquid fraction, ensuring mass conservation. This model is applied to study cases with gaseous, vaporous or pseudo-cavitation through the use of the Rayleigh–Plesset equation to characterize the physical behavior of the bubbles formed taking into account the characteristic time of each phenomenon. High resolution schemes are used for the spatial treatment of the advection and a temporal discretization based on the Strang splitting method which allows for a second order convergence in space and time. The numerical results obtained are contrasted and discussed with experimental data found for static and dynamic bearings for the three types of cavitation mentioned, obtaining a very good agreement.

Enhancing journal bearing performance through surface texturing: A comprehensive review of latest developments and future prospects

Incorporating surface textures on the contact points substantially improve bearing performances, which is evident from burgeoning interest in this field. This study thoroughly reviews existing literature on the topic from its inception to date. We have carried out an assiduous examination of various surface microcavities to assess how well they perform in terms of load-bearing capacity, friction coefficient, and friction force. The study briefly dwells upon numerical modeling techniques and their advantages and limitations. Further, this study develops a quantitative understanding of the impact of four textures including Pocket, Line, Cross, and Dot-like texture on the bearing parameters such as coefficient of friction, film thickness, and convergence ratio at the inlet and exit. The study elucidates how various surface textured designs would affect the way a hydrodynamic journal bearing functions . The present study also examines the texture roughness pattern transverse and longitudinal sinusoidal, full, and half-wave and its influence on the hydrodynamic journal bearing performance. The study gets concluded with the finding that in the case of pocket texture, the coefficient of friction is reduced by up to 20%. Transverse and longitudinal positive full wave texture pattern increase load-bearing capacity by up to 34% and reduces friction coefficient by up to 18%.

Parametric optimisation on the performance of the journal bearing using Taguchi approach

Hydrodynamic journal bearings are widely used to support high-speed rotating equipment due to their excellent strength and load-bearing capacity. Therefore, bearings are essential mechanical elements to improve the quality of rotating equipment. Bearing performance depends on various factors but pressure and frictional torque plays a vital role in load carrying capacity of bearing. In this present work, both experimental and analytical approach of a typical journal bearing has been carried out to determine the optimal performance of the bearing. Taguchi-based optimisation method has been proposed for journal bearing. Taguchi L27 orthogonal array has been planned to study peak pressure and frictional torque with three input parameters speed, load and viscosity index. The result shows that loading criterion influences much on performance of bearing. The experimental data is obtained from a journal bearing test rig and the analytical data are generated by MINITAB 18. From the experiment, it can be confirmed that speed – 2000 rpm, load – 600 N and viscosity index – 150 are the ideal process parameters for lower peak pressure and less frictional torque.

Design optimization of vein-bionic textured hydrodynamic journal bearing using genetic algorithm

Design optimization of vein-bionic textured hydrodynamic journal bearing using genetic algorithm

Environmentally acceptable lubricants (EAL) compared with a reference mineral oil as marine stern tube bearing lubricant – Experimental and theoretical investigations

The purpose of this research is to indicate the potential differences in bearing characteristics resulting from the application of different lubricant types with the same viscosity grade. The effect of different environmentally acceptable lubricants (EALs) on hydrodynamic journal bearing properties is studied experimentally and compared to the properties obtained after lubrication with a reference mineral oil. The results of the studies proved that a bearing lubricated with EALs had practically the same properties as one lubricated with mineral oil. The calculations for the tested bearing system showed that the variations of selected lubricant parameters, such as specific heat or thermal conductivity, do not significantly affect the properties of the bearing, i.e. the minimum film thickness or power losses.

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.

Effect of texture shapes and additives in lubricants on the dynamic characteristics of the hydrodynamic journal bearing

PurposeThis study aims to understand how the texture shape, number of textures and addition of nanoparticle additives in lubricants impact the dynamic characteristics of journal bearing by comparing six different texture shapes like triangle, chevron, arc, circle, rectangle and elliptical applied in pressure-increasing region under various geometrical and operating conditions.Design/methodology/approachThe finite element method approach has been employed to solve governing Reynold’s equation, assuming iso-viscous Newtonian fluid, for computation of performance parameters like stiffness and damping coefficient, threshold speed, etc. By using a regression model, the impact of adding nanoparticles Al2O3 and CuO to the base lubricant on viscosity variation is calculated for selected temperature ranges and weight fractions of nanoparticles.FindingsThe arc-shaped texture with an area density of 28.27%, eccentricity ratio of 0.2 and texture depth of 0.6 exhibited 35.22% higher direct stiffness and 41.4% higher damping coefficient compared to the lowest value in the circle-shaped texture. Increasing the number of arc-shaped textures on the bearing surface with low area density led to declining stiffness and damping parameters. However, with nanoparticle additives, the arc-shaped texture further showed 10.75% and 8.11% improvement in stiffness and 9.99% and 4.87% enhancement in damping coefficient for Al2O3 and CuO, respectively, at 90 °C temperature and 0.5% weight fraction.Originality/valueBy understanding the influence of texture shapes on the dynamic characteristics, engineers can design bearings that exhibit improved stability and enhance overall performance.

Modelling and Simulation of Aerodynamic Cylindrical Bearings Using ANSYS Hydrodynamic Bearing Element Types

Modern power engine concepts and environmental restrictions demand oil-free lubrication of rotors, for example, by gas bearings. However, the stiffness and damping properties ruling the rotor’s dynamics are poorly documented for aerodynamic bearings and simple calculation methods are lacking. Based on the similarity between aerodynamic and hydrodynamic journal bearings, it is investigated to what extent the hydrodynamic bearing element types of the commercial FE program ANSYS are also suitable for air bearings. Within these elements, the compressibility of the gas is neglected. After verification of the ANSYS hydrodynamic element types with literature data for cylindrical hydrodynamic bearings, the stiffness and damping coefficients of a cylindrical aerodynamic bearing are calculated by using the ANSYS hydrodynamic element types. In the examined speed range, the results agree well with literature data that consider gas compressibility. Therefore, the FE elements designed for hydrodynamical journal bearings may also be used for simulating cylindrical aerodynamic bearings. The presented calculation approach provides a compact and easy-to-use method for rotordynamic simulations with cylindrical aerodynamic bearings in a single development environment.

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.

Static Characteristics of Water-Lubricated Hydrodynamic Spiral-Groove Journal and Thrust Bearings for Motorized Spindle

Abstract Oil-lubricated hydrodynamic bearing is a typical support for motorized spindle. However, a motorized spindle supported by the oil-lubricated hydrodynamic bearing has disadvantages regarding high-temperature rise and low rotational speed. To overcome this problem, this technical brief proposes novel water-lubricated hydrodynamic spiral groove bearings for the motorized spindle. A rotor-bearing static model for the motorized spindle was established considering the external loads and the tilting effect of bearings. An experimental prototype for the motorized spindle was developed, and the theoretical calculation and experimental research on the bearing static characteristics were carried out. The result shows that the water-lubricated hydrodynamic spiral groove bearings have significant advantages in terms of low-temperature rise, good high-speed performance, and moderate spindle stiffness, together with the inherent low manufacture cost and high rotation accuracy of the bearings, and the proposed bearings can be a potential alternative to the fluid bearing for the high-speed motorized spindle.

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.

ANALYSIS OF FLOW AND TEMPERATURE DISTRIBUTION IN JOURNAL BEARING LUBRICATED WITH VEGETABLE OIL

The use of vegetable oil as a sustainable alternative to mineral oil in lubrication applications has garnered considerable attention. This research focuses on evaluating three different vegetable oils, namely palm mid olein (PMO), refined bleached deodorized palm oil (RBDPO), and rapeseed oil, for their effectiveness in lubricating a hydrodynamic journal bearing. The study examines key performance factors such as pressure, temperature, load-carrying capacity, and coefficient of friction. Computational fluid dynamics (CFD) is employed to compare the lubricating capabilities of the vegetable oils against engine oil. Rapeseed oil emerges as the most promising option among the vegetable oils, displaying notable advantages. It demonstrates a 22.12% higher pressure, 26.37% higher load-carrying capacity, and 0.37% higher temperature distribution compared to PMO. In contrast, while engine oil exhibits a 16.67% higher pressure distribution and 35.8% higher load-carrying capacity, it also comes with a drawback of 44.29% higher coefficient of friction compared to other vegetable oils. It is worth noting that the simulation results have been validated through experimental data, leading to the conclusion that engine oil surpasses vegetable oils in terms of pressure and temperature distribution.

Time History of Maximum Bearing Temperature Based on a Simplified Thermohydrodynamic Lubrication Theory

An overshoot phenomenon of bearing temperature in hydrodynamic journal bearings may be observed during a sudden start-up experiment. This phenomenon implies that the maximum bearing temperature in acceleration operation may exceed the predicted one which can be predicted accurately by applying a state-of-the-art steady state thermohydrodynamic lubrication (THL) model. This paper presents the maximum bearing temperature including the one during acceleration operation by using a simplified THL model that is newly proposed for a transient THL analysis. It is found that the overshooted temperature can be qualitatively predicted by using the transient THL model that incorporates properly the interaction between the motion of journal center and the viscous dissipation, even if it is a simple model. Next, the transient temperature during slow acceleration operation and also those toward higher dimensional steady state journal rotational speed are calculated and they are found to be in qualitative agreement with the measurements. The oil film characteristics such as oil film pressure, temperature and thickness after reaching the steady state equilibrium do not depend on the value of initial journal eccentricity ratio in the transient analysis. However, when the values are different, the characteristics immediately after starting rotation change largely. In the case of the value 1.00, it is found to give a prediction that agrees qualitatively with the characteristics measured in the experiment.

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].