Hole-entry Hybrid Journal Bearing Research Articles

Effect of Wear on Symmetric Hole-Entry Hybrid Journal Bearing Compensated by Orifice Restrictor Under Turbulent Regime

This study examines the impact of wear and turbulent flow on symmetric hole-entry hybrid journal bearings with orifice restrictors. Dufranes’s abrasive model for wear effect and Constantinescu’s lubrication model for turbulent flow have been used. A modification has been made to the Reynolds equationand utilized the finite element method to solvealong withflow equation of an orifice restrictor. For selected wear depth parameter values and Reynolds numbers,computed results have been acquired. The minimum fluid film thickness increases for worn bearings when operating under a turbulent regime rather than a laminar regime. Further, the stiffness coefficient decreases for constant external load when worn/unworn bearings function in a turbulent regime.

Improvement in textured hole-entry hybrid journal bearing system by using multi-objective genetic algorithm

Improvement in textured hole-entry hybrid journal bearing system by using multi-objective genetic algorithm

Analysis of the effect of oil inlet size on the static performance characteristics of non-Newtonian lubricated hole-entry hybrid journal bearings

Abstract In this study, the influence of inlet pocket size on the static performance of non-Newtonian lubricated hole-entry hybrid journal bearings is theoretically analyzed. The oil film of the bearing is discretized into a nonuniform mesh containing the geometric characteristics of the oil inlet pocket, and the inlet pocket is treated as a micro-oil recess. The Reynolds equation is solved by the finite element method based on Galerkin's techniques, and a new solution strategy to solve the recess/pocket pressure is proposed. The power-law model is used to introduce the non-Newtonian effect. The results show that the static performance characteristics of this type of bearing are greatly affected by the pocket size at both zero speed and high speed.

Numerical study of nonlinear stability boundaries for orifice-compensated hole-entry hybrid journal bearings

A high-performance and finite-length bearing system requires that the shaft can be stabilized even under a strong perturbation. The linear stability theory neglects the effects of nonlinear forces and the initial point of the shaft. Therefore, the stability of the bearing system is largely determined by the rotating speed of the shaft. In the present numerical investigation, the nonlinear forces and initial point of the shaft are accounted for to obtain the nonlinear stability boundary. The objective of this study is extended to orifice-compensated and hole-entry hybrid journal bearings with finite length. The critical rotating speed and the shaft center trajectory are acquired by solving Reynolds equation using the finite element method. By identifying the states of the orbits (stable or unstable), the nonlinear stability boundaries can be obtained. Results show that for the hybrid bearing system under the nonlinear conditions, the critical speed is a determinant factor while the initial location is another key factor. The shaft can be unstable if the initial point is outside of the stability boundary, although the speed is lower than the critical speed. There exists an obvious transitional region between the stable and unstable condition when the speed approaches the critical speed.

Study of Surface Roughness Effect on the Performance of Multilobe Hybrid Journal Bearing

In this paper, influence of surface roughness on the performance of two lobe and three lobe symmetric non-recessed hybrid journal bearing system has been presented. A modified form of Reynolds' equation using flow factors on the similar line of Patir and Cheng model and flow restrictor equation have been solved by finite element method. In this study, the consequence of roughness orientations on the bearing surfaces on the performance of a 2- lobe and 3-lobe symmetric hole entry hybrid journal bearing are presented for different bearing geometries defined by offset factor (δ=0.9, 1.0 and 1.1). The results of the study indicate that the surface orientation have noteworthy effect on the bearing performance characteristics. An enhanced threshold speed margin has been observed for longitudinal roughness pattern. Further, results of the study indicate that a proper choice of bearing configuration and bearing surface roughness orientation is essential to obtain better performance characteristics of capillary restrictor hybrid journal bearing system.

Performance comparison of hole-entry and slot entry hybrid journal bearings considering combined influence of thermal effects and micropolar lubricant

PurposeHybrid journal bearing have long been used in machines requiring large load and high speed capacity operating under wide range of temperatures. Different compensating devices are used in for efficient operation of bearings. This paper aims to help in selection of optimum compensating device by evaluating the comparative performance of constant flow valve, capillary compensated and slot entry hybrid journal bearing under the combined influence of thermal effects and micropolar nature of lubricant.Design/methodology/approachThe variation in micropolar parameters and viscosity change due to temperature increase of lubricant are considered in present study. Finite element method is used for combined iterative solution of micropolar Reynolds, energy and conduction equations. Micropolar lubricant is assumed to be governed by two parameters, coupling number and characteristic length. The results in the study are presented for symmetric and asymmetric configurations of hole entry and slot entry non-recessed hybrid journal bearingsFindingsThe results indicate that constant flow valve compensated hole entry hybrid journal bearing is the highest performing bearing for the given range of micropolar parameters of lubricant in terms of maximum fluid pressure and dynamic coefficients.Originality/valueThe performance variations of various configurations of hybrid journal bearing are presented in a single paper. The reader can get overview of combined effects of micropolar parameters and viscosity decrease due to temperature increase of the lubricant.

A Study on the Influence of Combined Elastic and Micropolar Effects on Hole-Entry Hybrid Journal Bearing

A Study on the Influence of Combined Elastic and Micropolar Effects on Hole-Entry Hybrid Journal Bearing

Nonlinear transient analysis of hole-entry journal bearing with constant flow of micropolar fluids

The present work deals with study and analysis of a symmetric hybrid journal bearing compensated with constant flow valve restrictor operating with micropolar fluid from stability point of view. The effect of micropolar parameters on the stability of this journal bearing system is presented on the basis of nonlinear transient model. Finite element method has been used to solve modified Reynolds’ equation for the flow of micropolar fluid through the bearing. Computations are done for the static and dynamic characteristics of hole-entry hybrid journal bearing system. The stability characteristics in terms of critical mass of journal, threshold speed, and frequency of whirl are obtained for journal bearing system operating with Newtonian and micropolar fluids and are compared together. Paths of the journal center in the form of trajectories have also been plotted using the journal center coordinates obtained after solving nonlinear equation of motion by fourth-order Runge–Kutta method to find the stability margin of the considered bearing configuration more precisely and easily. Results indicate that micropolar effect causes significant increase in stability margin of the hybrid journal bearing system especially at higher loads. The results also indicate that lubricant flow through the bearing and type of lubricant should be decided in an appropriate manner for the stability of the constant flow valve compensated hybrid journal bearing system.

Electro-rheological fluid lubricated textured multi-lobe hole-entry hybrid journal bearing system

Lubrication of fluid film bearings with smart lubricants provides better dynamic behavior. The behavior of these smart lubricants is described by Bingham model of non-Newtonian fluid flow. In the r...

Behaviour of two-lobe hole-entry hybrid journal bearing system under the combined influence of textured surface and micropolar lubricant

PurposeThe aim of the present paper is to study the combined influence of textured surface and micropolar lubricant behaviour on the performance of two-lobe hole-entry hybrid journal bearing system. The bearing performance parameters of the textured circular/two-lobe hole-entry hybrid journal bearing system have been computed against the constant vertical external load supported by the bearing.Design/methodology/approachIn this work, Eringen’s micropolar fluid theory has been used to derive the governing Reynolds equation. The consequent solution of the governing Reynolds equation has been obtained by using finite element method (FEM) numerical technique.FindingsThe present study indicates that the use of the textured surface, two-lobe profile of bearing and micropolar lubricant, significantly enhances the bearing performance as compared to non-textured circular journal bearing.Originality/valueThe present study concerning the influence of surface texturing on the behaviour of the two-lobe hole-entry hybrid journal bearing lubricated with micropolar lubricant is original. The theoretically simulated results of the present study will be useful to design an efficient journal bearing system.

Performance of two-lobe hole-entry hybrid journal bearing system under the combined influence of textured surface and couple stress lubricant

Textured surface in journal bearings is becoming an important area of investigation during the last few years. Surface textures have the shapes of micro-dimple with a small diameter and depth having order of magnitude of bearing clearance. This paper presents the influence of couple stress lubricant on the circular and non-circular hole-entry hybrid journal bearing system and reports the comparative study between the textured and non-textured circular/non-circular hybrid journal bearing system. The governing Reynolds equation has been modified for the couple stress lubricant flow in the clearance of bearing and journal. The FEM technique has been applied to solve the modified Reynolds equation together with restrictor flow equation. The numerically simulated results indicate that the influence of couple stress lubricant is significantly more in textured journal bearing than that of non-textured journal bearing. Further, it has been observed that the textured two-lobe (δ = 1.1) hybrid journal bearing lubricated with couple stress lubricant provides larger values of fluid film stiffness coefficients and stability threshold speed against other bearings studied in the present paper.

Effect of Couple Stress Lubrication on Symmetric Hole-Entry Hybrid Journal Bearing

The present study deals with capillary compensated symmetric hole-entry hybrid journal bearing under couple stress lubricant. Reynolds equation has been modified considering couple stress lubricant in the bearing system. The Galerkin’s Technique has been applied to solve the modified Reynolds equation together with restrictor flow equation. The computation of bearing performance has been made by using couple stress parameter. The bearing operating with couple stress lubricant provides better values of fluid film thickness, rotor dynamic coefficients than similar bearing operating with Newtonian lubricant.

Performance Analysis of Capillary Compensated Hybrid Journal Bearing by Considering Combined Influence of Thermal Effects and Micropolar Lubricant

The viscous dissipation of micropolar lubricant results in temperature increase of hole-entry hybrid journal bearing. Thermohydrostatic (THS) performance characteristics are computed by the concurrent solution of micropolar Reynolds, micropolar energy, and conduction equations. The results obtained numerically indicate that bearing is significantly affected by increase in temperature. Hence, it is essential to consider the thermal effects for bearing operating with micropolar lubricant to produce realistic bearing characteristic data.

Nonlinear transient response of rough symmetric two lobe hole entry hybrid journal bearing system

The present paper describes the effect of surface roughness orientation pattern on the nonlinear transient response of symmetric two lobe capillary compensated hole entry hybrid journal bearing. Nonlinear equations of motion have been solved with the Runge-Kutta method. The stability of the journal bearing system has been studied by obtaining the journal center motion trajectories. The results of the study reveal that the surface roughness pattern significantly changes the stability of capillary compensated two lobe hole entry hybrid journal bearing. Hence, from the bearing stability point of view, a proper selection of the surface roughness pattern and bearing geometry is essential.

Thermohydrostatic analysis of hybrid journal bearing compensated by constant flow valve operating with micropolar lubricant

This research article deals with numerical study of micropolar lubrication in constant flow valve compensated hole entry hybrid journal bearing by considering the thermal effects. The bearing performance characteristics are computed by the solution of modified Reynolds, three-dimensional energy, and three-dimensional conduction equations. The results obtained numerically indicate that bearing performance is significantly affected by increase in temperature. Hence it is imperative to consider the thermal effects for bearing operating with micropolar lubrication to generate realistic bearing characteristic data.

Analysis of Noncircular Hole-Entry Capillary-Compensated Hybrid Journal Bearing with Micropolar Lubrication

ABSTRACTThis article presents the analysis of a two-lobe hole-entry hybrid journal bearing operating with micropolar lubrication. The modified Reynolds equation governing the laminar flow of isoviscous, incompressible micropolar lubricant in the clearance space of a journal bearing system has been solved using a finite element model incorporating appropriate boundary conditions. A comparative analysis between circular and noncircular two-lobe hybrid journal bearings with capillary restrictor under Newtonian and micropolar lubrication has been presented. It is concluded that bearing performance characteristics are significantly influenced by micropolar lubrication.

A study of 2-lobe symmetric hole entry hybrid journal bearing operating with non-Newtonian lubricant considering thermal effects

This paper presents the thermohydrostatic solution of 2-lobe symmetric hole entry hybrid journal bearing compensated with orifice restrictor and operating with cubic law lubricant. Simultaneous solutions of Reynold׳s, energy and conduction equations have been obtained by using finite element method and a suitable iterative scheme. The performance characteristics parameters of 2-lobe symmetric bearing system have been presented for various bearing geometries and nonlinearity factors. The numerically simulated results of the study indicates that the variation of viscosity of cubic law lubricant due to temperature rise and bearing geometry changes the bearing performance quite significantly.

Surface Roughness Effect on the Performance of 3-lobe Symmetric Hole Entry Hybrid Journal Bearings

The present paper, evaluates the effect of surface roughness on the performance characteristics of capillary compensated 3-lobe symmetric hole entry hybrid journal bearing. The effect of surface roughness patterns viz; transverse, isotropic, longitudinal and smooth, on bearing performance is presented for different values of offset factor. A modified form of Reynold’s equation in conjunction with restrictor flow equation is solved by using Galerkin’s technique of FEM. The numerically simulated results of the study indicate that the surface roughness orientation patterns affect the performance of 3-lobe hybrid journal bearing system significantly. Further, it is noticed that the longitudinal roughness pattern provides enhanced value of rotor dynamic coefficient.To have an improved dynamic performance, a judicious selection of offset factor and surface roughness pattern parameter is essential.

Thermohydrostatic rheological analysis of constant flow valve compensated multiple hole-entry hybrid journal bearings

Purpose – The changing technological scenario necessitated hybrid journal bearings to operate under severe conditions of heavy load and high speed resulting into temperature rise of the lubricant fluid-film and bearing surface. To predict the performance of a bearing realistically, theoretical model must consider the combined influence of the rise of temperature and non-Newtonian behavior of the lubricant. The aim of the present paper is to study the effect of viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on performance of constant flow valve compensated multiple hole-entry hybrid journal bearings. Design/methodology/approach – Finite element method has been used to solve Reynolds equation along with restrictor flow equation, 3D energy equation and 3D conduction equation using suitable iterative technique. The non-Newtonian lubricant has been assumed to follow cubic shear stress law. Findings – The thermohydrostatic rheological performances of symmetric and asymmetric hole-entry hybrid journal bearing configurations are studied. The computed results illustrate that variation of viscosity due to rise in temperature and non-Newtonian behavior of the lubricant affects the performance of hole-entry hybrid journal bearing system quite significantly. Originality/value – In the present work, the influences of the viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on the performance characteristics of non-recessed hole-entry hybrid journal bearing with symmetric and asymmetric configurations compensated with constant flow valve restrictors have been investigated for generating the design data to be used by bearing designer. The design data computed in the present thesis are a contribution in field of knowledge of bearing design.

Thermohydrostatic rheological study of orifice compensated asymmetric hole-entry hybrid journal bearings

Purpose – The purpose of this paper is to describe the static performance characteristics of orifice compensated hole-entry hybrid journal bearing considering the combined influence of rise in temperature and non-Newtonian behavior of the lubricant. The required governing equations have been solved using the finite element method and a suitable iterative technique. The non-Newtonian lubricant has been assumed to follow the cubic shear stress law. The thermohydrostatic (THS) rheological performance of asymmetric hole-entry hybrid journal bearing configurations are studied. The computed results indicate that variation of viscosity due rise in temperature and non-Newtonian behavior of the lubricant affects the performance of asymmetric hole-entry hybrid journal bearing system quite significantly. Design/methodology/approach – The THS rheological solution of a hole-entry hybrid journal bearing system requires the simultaneous solution of Reynolds equation, 3D energy equation and 3D conduction equation along w...