Slot-entry Hybrid Journal Bearing Research Articles

Effect of bearing shell deformation and ER fluid behavior on two-lobed slot-entry hybrid journal bearing

The present article deals with the effects of deformable bearing shells on the performance of lobed slot-entry hybrid journal bearing systems. The influence of the deformation coefficient [Formula: see text] has been studied using the thin liner elasticity model, which measures the flexibility of the bearing liner. Recently, smart fluid, that is, electrorheological (ER) fluid has been used in various tribological systems to obtain better performance. Therefore, the influence of ER lubricant on the bearing performance characteristics has also been studied in this work. Bingham model constitutive relation has been used to analyze the non-Newtonian behavior of ER fluid. The performance of fluid film bearings is greatly influenced by the noncircularity of the bearings. Therefore, the behavior of deformable bearing shells in a slot-entry journal bearing for lobed conditions has also been studied in the present study. The results reveal that considering deformation in the bearing shell reduces the value of frictional torque, whereas the value of stiffness coefficients and stability threshold speed increases. However, ER lubricant enhances the value of film thickness, stiffness/damping coefficients, and stability threshold speed margin.

A Simulation Study on the Behavior of Magnetorheological Fluid on Herringbone-Grooved Hybrid Slot-Entry Bearing

In recent years, extensive use of smart lubricants has been made in order to control the tribological performance of fluid film bearings. The grooved surfaces of the journal bearing greatly influence the performance of bearings. In the present work, various geometric shapes of herringbone grooves (rectangular, triangular, and parabolic) with groove angles (30° and 60°) have been considered to numerically simulate the performance of slot-entry bearings. The work reported in this article deals with the numerical simulation of magnetorheological (MR) fluid–lubricated slot-entry herringbone-grooved hybrid journal bearings. Dave equation, a constitutive relation of the Bingham model, was employed to simulate the flow behavior of MR fluid. Using the finite element method (FEM), the governing Reynolds equation for a hybrid slot-entry bearing model was solved. The result shows that the use of a herringbone-grooved surface and application of MR fluid in a slot-entry bearing offers better stability and higher fluid film stiffness and minimizes frictional torque.

A study on performance of slot entry hybrid journal bearing considering effect of surface irregularities

PurposeThis study aims to deal with the performance of symmetric/asymmetric slot entry hybrid journal bearing system considering the effect of three dimensional irregularities in the analysis.Design/methodology/approachThe asperity profile of three-dimensional irregularities has been modeled in both circumferential and axial directions. To compute the bearing performance characteristics parameter, finite element formulation of governing Reynolds equation has been derived using Galerkin’s technique.FindingsBased on the numerically simulated results, it has been observed that the three-dimensional irregularities enhance the value of minimum fluid film thickness (h̄min), lubricant flow (Q̄) and fluid film damping coefficients (C̄11,C̄22) approximately by order of magnitude of 24-26, 43-51 and 18-66 per cent, respectively, for the case of asymmetric slot entry configuration. Whereas, the values of fluid film stiffness coefficients (S̄11,S̄22) and threshold speed (ω̄th) reduces approximately by order of 1-6 and 0-3 per cent, respectively, for the case of symmetric slot entry configuration.Originality/valueThe present paper describes that the influence of three-dimensional irregularities on bearing surface on the performance of slot entry hybrid journal bearing is original in literature gaps. The numerically simulated results presented in this study are expected to be quite useful to the bearing designers.

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.

Investigation of the micropolar lubricant and thermal effects in the slot entry hybrid journal bearings

The present article studies the combined influence of the micropolar lubricant and thermal effects in the slot entry hybrid journal bearings. Bearing performance characteristics are computed by the concurrent solution of modified Reynolds, three-dimensional micropolar energy, and three-dimensional conduction equations. Thermohydrostatic characteristics of the slot entry hybrid journal bearings have been studied vis-à-vis isothermal characteristics. The results obtained numerically indicate that isoviscous assumption of the lubricant is incorrect and the bearing performance is significantly affected by the increase in temperature. Hence, it is essential to consider the thermal effects for the bearings operating with the micropolar lubricant for reliable performance analysis of the bearings.

Influence of couple stress lubricant on the performance of textured two-lobe slot-entry hybrid journal bearing system

This paper concerns with theoretical investigation to predict the combined influence of textured surface and couple stress lubricant behavior on the performance of circular/two-lobe slot-entry hybrid journal bearing. The flow of incompressible couple stress lubricant through the clearance of a textured journal bearing system is governed by the modified Reynolds equation. The modified Reynolds equation has been derived on the basis of Stokes micro-continuum theory and is solved using a finite element method technique for computing the bearing performance characteristics parameters. The static and dynamic characteristics of circular/two-lobe slot-entry hybrid journal bearing have been computed for textured and non-textured bearings with influence of couple stress lubricant. The present study indicates that the influence of couple stress lubricant behavior is significantly more on the values of fluid film stiffness coefficients [Formula: see text], critical mass of journal [Formula: see text], and stability threshold speed margin [Formula: see text] for textured surface than that of non-textured surface in case of a slot-entry hybrid journal bearing system.

Influence of wear on the performance of 2-lobe slot entry hybrid journal bearings

In the present paper, the influence of wear on the performance of 2-lobe slot entry restrictor bearing has been investigated theoretically. The equation of fluid flow field has been solved by using Galerkin’s technique of FEM. In this study, Dufrane’s wear model has been used to consider the change in bush geometry due to wear. The performance of 2-lobe slot entry restrictor bearing is studied for both symmetric and asymmetric slot configurations. The simulated results of the study indicate that the wear defect substantially changes the performance of 2-lobe slot entry journal bearing systems. A proper choice of bearing geometry and bearing configuration (12 slots and 6 slots per row) may partially compensate the loss occurred due to wear.

Comparison of static performance characteristics of different configurations of slot-entry hybrid journal bearing operating with non-Newtonian lubricants

Purpose – The slot-entry hybrid journal bearings have been successfully used in various engineering applications because of their good performance over wide range of speed and load, besides their relative simplicity in manufacturing. Most of the research work pertaining to non-recessed journal bearing assumes standard symmetric and asymmetric configurations. However, many more configurations are possible by changing the position of slot which may improve the performance of the slot-entry journal bearing. In the present work study of static performance characteristics of slot-entry journal bearing of different configuration has been carried out. The paper aims to discuss these issues. Design/methodology/approach – FEM has been used to solve the Reynolds equation governing the flow of lubricant in the bearing clearance space along with the restrictor flow equation. The non-Newtonian lubricant has been assumed to follow the cubic shear stress law. The performance characteristics of slot-entry hybrid journal bearings are computed by developing a computer program. Findings – The simulated results of bearing characteristics parameters in terms of minimum fluid-film thickness and bearing flow have been presented for the wide range of various values of non-linearity factor and external load. It is found that there is an increase in the oil requirement for slot-entry hybrid journal bearing with the specified operating and geometric parameters, when the viscosity of the lubricant decreases due to the non-Newtonian behavior of the lubricant. The effect of the decrease in the viscosity of the lubricant due to non-Newtonian behavior of the lubricant diminishes the attitude angle. The computed performance characteristics are helpful for the bearing designer while choosing a particular configuration of bearing. Research limitations/implications – The performance characteristics have been computed by considering the non-Newtonian lubricants. The thermal effects have been ignored in the analysis so as to obviate the mathematical complexity. Originality/value – Get idea from already published manuscripts.

Influence of micropolar lubricants on the performance of slot-entry hybrid journal bearing

A theoretical study concerning the slot-entry hybrid journal bearing lubricated with micropolar lubricants is presented. The modified Reynolds equation for micropolar lubricant is solved using finite element method along with equation of lubricant flow through slot-entry restrictors as a constraint together with appropriate boundary conditions. It has been observed that a slot-entry hybrid journal bearing operating with micropolar lubricant shows an increase in the value of minimum fluid film thickness and a reduction in the value of coefficient of friction as compared to a corresponding similar slot-entry hybrid journal bearing operating with Newtonian lubricant.

Performance of Asymmetric Slot-Entry Hybrid Journal Bearing Operating with Non-Newtonian Lubricant

This article presents the theoretical investigations of the rheological effects of the lubricant on the performance of asymmetric slot-entry hybrid journal bearing system. Finite element method (FEM) has been used to solve the Reynolds equation governing the flow of lubricant in the bearing clearance space along with the restrictor flow equation. The non-Newtonian lubricant has been assumed to follow the cubic shear stress law. The simulated results of bearing characteristics parameters in terms of minimum fluid film thickness and bearing flow have been presented for the wide range of values of nonlinearity factor and external load. The computed results reveal that the variation of viscosity due to non-Newtonian behavior of the lubricant affects the performance of slot-entry hybrid journal bearing system quite significantly.

A Comparative Thermal Analysis of Slot-Entry and Hole-Entry Hybrid Journal Bearings Lubricated With Non-Newtonian Lubricant

The effect of viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on the performance of hole-entry and slot-entry hybrid journal bearings system is the focus of this investigation. The performance characteristics of nonrecessed hybrid journal bearings operating with different flow controlling devices, i.e., constant flow valve, capillary, orifice, and slot restrictors, have been compared. Finite element method has been used to solve the Reynolds equation governing the flow of lubricant in the bearing clearance space along with the restrictor flow equation, energy equation and conduction equation using suitable iterative technique. The non-Newtonian lubricant has been assumed to follow the cubic shear stress law. The results indicate that variation in viscosity due to rise in temperature and non-Newtonian behavior of the lubricant affects the performance of nonrecessed hybrid journal bearing system quite significantly. The results further indicate that bearing performance can be improved by selecting a particular bearing configuration in conjunction with a suitable compensating device.

Performance of slot-entry hybrid journal bearings considering combined influences of thermal effects and non-Newtonian behavior of lubricant

This paper presents theoretical investigations of the thermal and rheological effects of lubricant on the performance of symmetric and asymmetric slot-entry hybrid journal bearing system. FEM has been used to solve the Reynolds equation governing flow of lubricant in bearing clearance space along with restrictor flow equation, energy equation and conduction equation using suitable iterative technique. The thermohydrostatic (THS) rheological performance of slot-entry hybrid journal bearings are studied for small temperature variation of the lubricant. The computed results reveal that variation of viscosity due to temperature rise and non-Newtonian behavior of lubricant affects the bearing performance quite significantly.

Thermohydrostatic analysis of slot-entry hybrid journal bearing

The present study describes the theoretical investigation into the static and dynamic performance of a slot-entry hybrid journal bearing system by considering variation of viscosity due to temperature rise of the lubricant in the analysis. Required governing equations have been solved using the finite element method and a suitable iterative technique. Thermohydrostatic performance of a symmetric as well as asymmetric slot-entry hybrid journal bearing configuration have been studied vis-à-vis their isothermal performance. The results presented in the study indicate that the variation of viscosity due to temperature rise of the lubricant fluid-film affects the performance of slot-entry hybrid journal bearing systems quite appreciably.

The Performance of Hybrid Journal Bearings in the Superlaminar Flow Regimes

Previous work conducted on hybrid journal bearings has shown that a combination of hydrostatic and hydrodynamic lubrication principles leads to good load support over a wide range of speeds, including zero speed. Above the transition speed, particularly with large bearing diameters or low-viscosity lubricants, the mode of flow within the fluid film degenerates from that of pure laminar flow, through a transitional or vortex flow regime, to fully developed turbulent flow. This work presents a theoretical investigation of slot entry hybrid journal bearings operating in the superlaminar flow regimes. In particular, the work considers the effects of superlaminar flow on the optimization of slot entry hybrid journal bearings.