Hole-entry Hybrid Journal Bearing System Research Articles

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

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.

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...

Thermal Analysis of Orifice-Compensated Symmetric Hole-Entry Hybrid Journal Bearings

The present work describes the fluid-film pressure ( p ) distributions, fluid-film thickness ( h ) profiles and fluid-film temperature ( T f ) distributions of orifice-compensated symmetric 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 computed results illustrate that variation of viscosity due to rise in temperature and non-Newtonian behavior of the lubricant affects the performance of symmetric hole-entry hybrid journal bearing system quite significantly.

A study of misaligned electrorheological fluid lubricated hole-entry hybrid journal bearing

The present work describes a theoretical study to demonstrate the effect of the journal misalignment on the performance of an orifice compensated hole-entry hybrid journal bearing system lubricated with ER fluid. The journal misalignment has been accounted for by defining a pair of misalignment parameters sigma and delta. Continuous Bingham Model has been used to describe the behavior of ER fluid. The bearing static and dynamic characteristic parameters presented in the study indicate that the effect of journal misalignment is in general to cause a reduction in bearing dynamic characteristic parameters whereas the electric field in the ER fluid is to partially compensate this loss.

Analysis of thermal effects in capillary compensated hole-entry hybrid journal bearings lubricated with a non-Newtonian lubricant

The present work describes the performance characteristics of the capillary compensated symmetric and asymmetric hole-entry hybrid journal bearing systems considering the combined influence of the temperature rise and the non-Newtonian behaviour 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 rheological performance of symmetric and asymmetric hole-entry hybrid journal bearing configurations is studied. The computed results show that the variation of viscosity due to the temperature rise and the non-Newtonian behaviour of the lubricant affects the performance of the hole-entry hybrid journal bearing system quite significantly.

Effect of Wear on the Performance of Non-Recessed Orifice Compensated Hybrid Journal Bearing

A bearing subjected to frequent start/stop operations is worn progressively due to rubbing. As a consequence, the geometry of the bearing changes and the performance is affected. This paper presents a theoretical study of the performance of an orifice compensated worn non-recessed hole-entry hybrid journal bearing system. The finite element method has been used to solve the Reynolds equation, governing the flow of the lubricant in the clearance space between the journal and the bearing, along with a restrictor flow equation. The global system equation with the orifice restrictor is nonlinear, which is solved by an iterative technique using the Newton-Raphson method. Two types of journal bearing configurations, having symmetrical and asymmetrical distribution of supply holes around the circumferential direction, have been investigated in the present study. The effect of the wear depth on the journal bearing performance characteristics have been presented for a wide range of restrictor design parameters and external loads. The study demonstrates that the wear affects the bearing performance parameters and the degree of variation is affected by the operating condition, the bearing configuration, and the type of restrictor used. The influence of wear can be reduced by a proper selection of the bearing configuration (symmetrical/asymmetrical), the restrictor, and its design parameter.

Influence of Surface Roughness on Non-Newtonian Thermohydrostatic Performance of a Hole-Entry Hybrid Journal Bearing

A general solution scheme to account the surface roughness and the cross-film viscosity variation of lubricant due to its non-Newtonian behavior and rise in fluid-film temperature for the analysis of fluid-film bearings is presented. The combined influence of surface roughness, non-Newtonian behavior of lubricant, and thermal effects on the performance of a hole-entry hybrid journal bearing system has been investigated. The surface roughness, especially stationary roughness (i.e., rough bearing and smooth journal) with a transverse pattern was found to partially compensate for the loss in load-carrying capacity due to the thermal and/or non-Newtonian behavior of lubricant effects. It limits 18.86% loss in load-carrying capacity due to the thermal effect to only 1.6% and 33.99% loss due to the combined influence of non-Newtonian lubricant and thermal effect to 16.76%.

Study of orifice compensated hole-entry hybrid journal bearing considering surface roughness and flexibility effects

The present work describes a theoretical study to demonstrate the combined influence of surface roughness and bearing flexibility on the performance of an orifice compensated hole-entry hybrid journal bearing system. The average Reynold equation governing the flow of lubricant in the clearance space between rough journal and bearing surfaces and 3-dimensional elasticity equation governing the displacement field in the bearing shell have been solved simultaneously using finite element method. The influence of transverse, isotropic and longitudinal roughness patterns on the performance of orifice compensated hole-entry journal bearing configuration have been studied for the various values of surface roughness parameter ( Λ), surface pattern parameter ( γ) and bearing shell deformation coefficient ( D ¯ c ) . The study indicate that the reduction in the bearing characteristic parameters such as load carrying capacity, fluid-film stiffness and damping coefficients due to the bearing shell flexibility effect can be partially compensated in roughened hole-entry flexible journal bearing system by making a proper selection of roughness patterns. The results presented in the study demonstrates that for an accurate prediction of bearing characteristic data, the consideration of combined influence of surface roughness and bearing flexibility effects in the analysis may be more appropriate to use.

On the restrictor design parameter of hybrid journal bearing for optimum rotordynamic coefficients

The precise design of bearings can be formulated after carefully studying both static and dynamic characteristics of journal bearing. The present paper deals with the investigation of restrictor design parameter of a capillary compensated hole–entry hybrid journal bearing system for optimum stiffness and dynamic coefficients of the bearing. The bearing flexibility and variation of viscosity due to temperature rise of the lubrication has been considered in the study. The numerical solution of governing equations, i.e. Reynold's, energy, heat conduction, and elasticity equations has been obtained using finite element method. The study includes performance of a double row symmetric hole–entry hybrid journal bearing configuration containing 12 holes per row. The results presented herein indicate that change in viscosity of lubricant and bearing flexibility affects the bearing design parameter, so the stability of rigid rotor also gets affected. The results show that theoretical modeling of the bearing presented in this work will certainly prove to be effective tool for the selection of restrictor design parameter, C ¯ s 2 for optimum stability parameters.

The Stability Margin of a Roughened Hole-Entry Hybrid Journal Bearing System

The present work describes a theoretical investigation into the effect of surface roughness on the stability margin of an orifice-compensated, hole-entry hybrid journal bearing system. A modified form of the average Reynolds equation is used for the solution of a lubricant flow field in the clearance space of a rough journal bearing system. The effects of surface roughness parameter (Λ), variance ratio (V̄rj), and the surface orientations (γ) on the bearing flow, load-carrying capacity, and stability threshold speed margin are studied. The study indicates that the bearing configurations having surface roughness on one of the opposing surfaces (stationary or moving roughness) show an opposite trend between stability threshold speed margin and load-carrying capacity. However, the bearing configurations having transverse- and isotropic-type roughness patterns on both bearing and journal surfaces provide an improved value of both stability threshold speed margin and load-carrying capacity only when the surface roughness has a variance ratio value between 0.49 and 0.59 for the transverse roughness pattern and between 0.59 and 0.84 for the isotropic roughness pattern.

Performance of an Orifice Compensated Hole-Entry Hybrid Journal Bearing System Considering Surface Roughness and Thermal Effects

The present study describes the static and dynamic performance of an orifice-compensated hole-entry hybrid journal bearing system considering the combined influence of surface roughness and thermal effects. The Dowson generalized Reynolds equation governing the flow of variable viscosity lubricant in the clearance space of a smooth journal bearing is modified using the flow factors developed by Patir and Cheng. The effects of surface roughness parameter Λ, variance ratio V̄rj, and the surface orientations vis-á-vis transverse, isotropic, and longitudinal roughness patterns on the performance characteristics of bearings are studied. The rough bearing and smooth journal combination (V̄rj = 0.0) with a transverse roughness pattern (γ = 1/6) is observed to show the largest predicted load-carrying capacity of the bearing. The smooth bearing and rough journal combination (V̄rj = 1.0) with a transverse roughness pattern shows the highest stability threshold speed margin.

Stability Margin of Hybrid Journal Bearing: Influence of Thermal and Elastic Effects

This paper deals with the stability margin of a constant flow valve compensated hole-entry hybrid journal bearing system considering bearing flexibility and variation of viscosity due to temperature rise of the lubricant. The journal temperature is computed on the basis of average fluid-film temperature and axisymmetric isothermal element is assumed. The coupled solution of Reynold’s, energy, conduction, and elasticity equations is obtained using finite element method. The performance of a symmetric and asymmetric hole-entry hybrid journal bearing configurations is studied. The results presented in the study indicate that the bearing flexibility and temperature rise of the lubricant fluid-film affects the performance of the hole-entry hybrid journal bearing system quite significantly and proper selection of restrictor design parameter is quite useful in maintaining the fluid film thickness and threshold speed of the journal.

Study of hole-entry hybrid journal bearing system considering combined influence of thermal and elastic effects

A theoretical model is developed to study the performance of a hole-entry hybrid journal bearing system by considering variation of viscosity due to temperature rise of the lubricant in the analysis. The deformation of bush due to fluid-film pressure and temperature has been considered to establish the modified fluid-film profile. The journal temperature is computed on the basis of the fluid-film temperature. The relevant governing equations have been solved using the finite element method and a suitable iterative technique. The thermoelastohydrostatic performance of an orifice compensated symmetric and asymmetric hole-entry hybrid journal bearing configurations has been studied for the chosen bearing operating and geometric parameters. The results presented in the study indicate that the variation of viscosity due to temperature rise of the lubricant fluid-film have a quite appreciable influence on the static and dynamic performance of a hole-entry hybrid journal bearing system.

On The Stability Margin of Hole-Entry Hybrid Journal Bearings Considering Viscosity-Temperature Variation

The present study describes the theoretical investigation into the stability margin of a constant flow valve compensated hole-entry hybrid journal bearing system considering the variation of viscosity due to temperature rise of the lubricant. The journal temperature is computed on the basis of average fluid-film temperature. The relevant governing equations are solved using a finite element method and a suitable iterative technique. The thermohydrostatic performance of symmetric and asymmetric hole-entry hybrid journal bearing configurations are studies. 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 hole-entry hybrid journal bearing system quite significantly.

Performance of Externally Pressurized Non-Recessed Roughened Journal Bearing System Operating with Non-Newtonian Lubricant

The present work describes the static and dynamic performance of an orifice compensated hole-entry hybrid journal bearing system considering the combined influence of surface roughness and non-Newtonian behavior of the lubricant. The modified form of average Reynolds equation has been used for the solution of the lubricant flow field in the clearance space of a rough journal bearing system. The non-Newtonian lubricant has been assumed to obey the power law model. The effects of surface roughness parameter (Λ), variance ratio (V̄ rj) and the surface orientations such as transverse, isotropic and longitudinal surface orientations on the performance characteristics of the bearing have been studied for various values of power law index (n). Scheduled for Presentation at the 58th Annual Meeting in New York City April 28–May 1, 2003