Combined Influence of Wear and Misalignment of Journal on the Performance Analysis of Three-Lobe Three-Pocket Hybrid Journal Bearing Compensated With Capillary Restrictor

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Satish C. Sharma ◽  
Vikas M. Phalle ◽  
S. C. Jain
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Fluid Film ◽  
Wear Depth ◽  
Fluid Film Thickness ◽  
Film Stiffness ◽  
Offset Factor ◽  
Bearing System

The multirecess noncircular hybrid journal bearings have been receiving wide importance in order to overcome the adverse effects on performance characteristics of multirecess circular journal bearings. During the lifetime of a machine, bearings are quite often required to be operated over a number of years and are subjected to several start and stop operations. As a consequence of this, the bush becomes progressively worn out and thereby changing the clearance space between journal and bearing. The present paper presents an analytical study investigating the effect of wear along with both aligned and misaligned conditions of journal on the performance of a capillary compensated three-lobe three-pocket hybrid journal bearing system for the various offset factors δ = 0.8,1.0, and 1.2. The wear caused on the bearing surface due to the transient (start/stop) operations has been modeled using Dufrane’s wear model. The modified Reynolds equation governing the flow of lubricant in the clearance space of a three-lobe multirecess worn hybrid journal bearing system along with both aligned and misaligned conditions of journal has been solved using an iterative scheme based on FEM. The influence of offset factor (δ), the wear depth parameter (δ¯w), and journal misalignment factors (σ¯,δ¯) on the performance of the three-lobe three-pocket hybrid journal bearing and three-pocket circular hybrid journal bearing system have been investigated. The results have been presented for the capillary compensated three-lobe three-pocket hybrid journal bearing system. The simulated results suggest that a bearing with a higher value of offset factor (δ>1) provides better static and dynamic performance characteristics as compared with a three-pocket circular journal bearing but the bearing with offset factor (δ < 1) is predominantly affected by the wear defect and misalignment of journal. The numerically simulated results suggest that the wear defect and offset factors significantly affect the bearing performance. Therefore, it becomes imperative to account for the influence of wear and offset factors during the design process so as to generate accurate data of bearing performance. The numerically simulated results have been presented in terms of maximum fluid-film pressure, minimum fluid-film thickness, lubricant flow rate, direct fluid-film stiffness, damping coefficients, and stability threshold speed margin. The present study demonstrates that the performance of bearing is significantly affected by wear along with both aligned and misaligned conditions of journal and the loss is partially compensated by keeping the offset factor δ>1.

A Study of Worn Hybrid Journal Bearing System With Different Recess Shapes Under Turbulent Regime

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
E. Rajasekhar Nicodemus ◽  
Satish C. Sharma
Keyword(s):  
Journal Bearing ◽  
Flow Equation ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Wear Depth ◽  
Geometric Shapes ◽  
Wide Range ◽  
Fluid Film Thickness ◽  
Film Stiffness ◽  
Bearing System

The objective of the present paper is to study analytically the influence of wear on the performance of a capillary-compensated, four-pocket, hybrid journal bearing system operating in a turbulent regime by considering various geometric shapes of recess. The present study deals with bearings having four different geometric shapes of recess, i.e., square, circular, elliptical, and triangular recessed bearings. The wear on the bearing surface is modeled using Dufrane’s abrasive wear model. The Reynolds equation based on Constantinescu’s turbulent lubrication theory has been solved using finite element method along with a restrictor flow equation as a constraint together with appropriate boundary conditions. The numerically simulated results have been presented for a wide range of nondimensional external loads, wear depth parameters, and Reynolds numbers. The numerically simulated results suggest that the combined influence of wear, turbulence, and geometric shape of recess significantly affects the bearing performance. It has been observed that a triangular recessed bearing provides a greater value of minimum fluid film thickness when operating in a turbulent regime. It is also noticed that direct fluid film stiffness coefficients get reduced significantly when bearings operate in a turbulent regime compared with a laminar regime. Further, it is observed that from the viewpoint of fluid film stiffness, a square recessed bearing is found to be most suitable when operating in a turbulent regime.

Performance of Two Lobe Multirecess Hybrid Journal Bearing Compensated With Capillary Restrictor

2007 ◽  
Author(s):  
Prashant Kushare ◽  
Satish C. Sharma ◽  
S. C. Jain ◽  
J. Sharana Basavaraja
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Favourable Effect ◽  
Improved Performance ◽  
Stiffness And Damping ◽  
Offset Factor ◽  
Bearing System

Multirecess hydrostatic/hybrid journal bearings are being used in many applications owing to their excellent characteristics. The Noncircular journal bearing configurations too are quite frequently used in high speed machinery as they are efficient, less costly and provide better shaft stability. The Two lobe bearing (elliptical bearing) are among the commonly used noncircular journal bearing configuration. The multilobe multirecess hybrid journal bearings have been developed to combine the features of noncircular and circular hybrid journal bearing configurations. In the present work a theoretical investigation of a two lobe multirecess hydrostatic/hybrid journal bearing system have been carried out. The multilobe journal bearing configuration is designed as an arc of the circle with the centre points placed on the symmetry line of the single lobe. The journal offset has been accounted by defining an offset factor ‘δ’. The finite element method has been used to solve the Reynolds equation governing the flow of lubricant in the clearance space of the journal bearing system. The bearing static and dynamic performance characteristics have been presented for the various values of the offset factors (0.75, 1, 1.25 and 1.50) for hybrid mode of operation of the bearing. The simulated results of the studies reveals that, a two lobe recessed hybrid journal bearing provides an improved performance in respect of fluid film stiffness and damping coefficients as compared to that of circular recessed journal bearing. It has been observed that for a multilobe bearing having offset factor more than one has a favourable effect on the dynamic performance characteristics of the two lobe bearing.

Finite element analysis of multirecess hybrid spherical journal bearing system

2019 ◽  
Vol 234 (11) ◽  
pp. 1798-1821
Author(s):  
Adesh K Tomar ◽  
Satish C Sharma
Keyword(s):  
Finite Element ◽  
Journal Bearing ◽  
Design Guidelines ◽  
Numerical Results ◽  
Fluid Film ◽  
Frictional Torque ◽  
Element Analysis ◽  
Fluid Film Thickness ◽  
Film Stiffness ◽  
Bearing System

The present work deals with finite element method analysis of a multirecess hybrid spherical journal bearing system. The governing equations have been discretized using Galerkin’s technique and are solved simultaneously using a suitable iterative technique. The effect of span angle on the static and dynamic behavior of a hybrid spherical journal bearing compensated with membrane restrictor is investigated in the present work. Numerical results indicate that larger values of span angle provide enhanced value of minimum fluid-film thickness [Formula: see text], reduced lubricant flow requirement [Formula: see text], and higher value of frictional torque [Formula: see text]. Further, the results have been compared with a correspondingly similar capillary-compensated bearing. The comparison of numerically results demonstrates that the value of direct fluid-film stiffness coefficient [Formula: see text] could be 45.90% higher than that of correspondingly similar capillary-compensated bearing. The numerical results presented in this work may be useful as design guidelines for a recessed hybrid spherical journal bearing.

Analysis of a Worn Multirecess Hydrostatic Journal Bearing System

2009 ◽  
Author(s):  
E. Vijaya Kumar ◽  
Vikas M. Phalle ◽  
Satish C. Sharma ◽  
S. C. Jain
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Flow Equation ◽  
Fluid Film ◽  
Wear Depth ◽  
Lubricant Flow ◽  
Wide Range ◽  
Fluid Film Thickness ◽  
Range Of Values ◽  
Bearing System

In recent times Hydrostatic journal bearings have received considerable amount of attention by the researchers on account of their excellent performance as compared to other class of bearings. The objective of the present paper is to presents an analysis of a four-pocket capillary-compensated worn hydrostatic journal bearing system. The FEM has been used to solve the Reynolds equation governing the flow of lubricant in the clearance space of a multirecess journal bearing system together with capillary restrictor flow equation as a constant. The bearing performance characteristics of a capillary compensated 4-pocket worn hydrostatic journal bearing have been presented for a wide range of values of external load and nondimensional wear depth parameters. The numerically simulated results of bearing characteristics parameters in terms of maximum fluid-film pressure, minimum fluid-film thickness, lubricant flow rate and fluid film reaction have been presented. The simulated results suggest that for an accurate prediction of bearing characteristics data it is essential to include the effect of wear in the analysis of the hydrostatic journal bearing system.

Influence of Semi Cone Angle on Performance of a Non-Recessed Hybrid Conical Journal Bearing

2015 ◽  
Author(s):  
Prashant G. Khakse ◽  
Vikas M. Phalle ◽  
S. S. Mantha
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Cone Angle ◽  
Performance Characteristics ◽  
Fluid Film ◽  
Damping Coefficient ◽  
Lubricant Flow ◽  
Wide Range ◽  
Speed Effect ◽  
Film Stiffness

The present paper describes the analytical approach to find the static and dynamic performance characteristics of a newly configured non-recess hole-entry hybrid conical journal bearing, considering the speed effect of journal compensated with capillary restrictors. Capillary restrictors are placed in the holes which are drilled over the periphery of the conical journal bearing. These holes are placed at an angle of 30 degree in the circumferential direction. The modified Reynolds equation which governs the lubricant flow in the clearance space of journal and bearing is solved by using Finite Element Method (FEM). The performance characteristics for the non-recess hole-entry hybrid conical journal bearing have been shown for wide range of restrictor design parameter (C̄s2 = 0.02–0.1) in terms of bearing flow, direct fluid film stiffness and direct fluid film damping coefficient for different semi cone angles γ = 5deg, 10 deg, 20 deg and 30 deg. The results obtained from the simulation indicates that the non-recess hole-entry hybrid conical journal bearing depicts important performance characteristics for bearing flow (Q) and fluid film stiffness which may be useful for bearing designer. However, the non-recess hole-entry hydrostatic conical journal bearing shows desirable performance for fluid film damping coefficient.

Performance Analysis of a Nonrecessed Hybrid Conical Journal Bearing Compensated With Capillary Restrictors

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Prashant G. Khakse ◽  
Vikas M. Phalle ◽  
S. S. Mantha
Keyword(s):  
Performance Analysis ◽  
Film Thickness ◽  
Journal Bearing ◽  
Fluid Film ◽  
Load Parameter ◽  
Radial Load ◽  
Wide Range ◽  
Bearing Stiffness ◽  
Fluid Film Thickness ◽  
Film Stiffness

The present paper deals with the performance analysis of a nonrecessed hole-entry hydrostatic/hybrid conical journal bearing with capillary restrictors. Finite element method has been used for solving the modified Reynolds equation governing the flow of lubricant in the clearance space of journal and bearing. The hole-entry hybrid conical journal bearing performance characteristics have been depicted for a wide range of radial load parameter (W¯r  = 0.25–1.5) with uniform distribution of holes at an angle of 30 deg in the circumferential direction. The numerically simulated results have been presented in terms of maximum fluid film pressure, minimum fluid film thickness, lubricant flow rate, direct fluid film stiffness coefficients, direct fluid film damping coefficients, and stability threshold speed. However, the proposed investigation of nonrecess hole-entry hybrid conical journal bearing shows important performance for bearing stiffness and minimum fluid film thickness at variable radial load and at given operating speed.

Influence of Wear on the Performance of Multirecess Hydrostatic Journal Bearing Operating With Micropolar Lubricant

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
E. Rajasekhar Nicodemus ◽  
Satish C. Sharma
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Flow Equation ◽  
Performance Characteristics ◽  
Wear Depth ◽  
Damping Coefficients ◽  
Load Line ◽  
Wide Range ◽  
Load Arrangement ◽  
Stiffness And Damping

The objective of the present work is to study theoretically the influence of wear on the performance of four-pocket capillary-compensated hydrostatic journal bearing operating with micropolar lubricant. In the present study, the lubricant containing additives and contaminants is modeled as micropolar fluid. The modified Reynolds equation for micropolar lubricant is solved using finite element method along with capillary restrictor flow equation as a constraint together with appropriate boundary conditions. The performance characteristics of a capillary-compensated four-pocket worn hydrostatic journal bearing operating with micropolar lubricant have been presented for a wide range of values of nondimensional external load, wear depth parameter, and micropolar parameters. The simulated results have also been presented for two different loading arrangements. In arrangement I, the load line acts through centers of the pockets, whereas in arrangement II, the load line bisects the land between two pockets. The simulated results suggest that a bearing lubricated with lubricant having higher micropolar effect has better static and dynamic performance characteristics as compared with Newtonian lubricant but the bearing lubricated with lubricant having higher micropolar effect is predominantly affected by the wear vis a vis static characteristics parameters as compared with Newtonian lubricant for both loading arrangements. However, in the case of stiffness and damping coefficients, loading arrangement II shows a significant higher enhancement in the value of direct stiffness and damping coefficients in z-direction due to micropolar effect as compared with load arrangement I. And also, the effect of wear on stiffness and damping coefficients in z-direction for bearing operating with micropolar lubricant is of same order as Newtonian lubricant for the loading arrangement II. A similar behavior is observed for the case of stiffness and damping coefficients in x-direction for loading arrangement I.

The Rolling-Pad Journal Bearing: A Promising Antiwhirl Configuration

1981 ◽  
Vol 23 (3) ◽  
pp. 131-141
Author(s):  
M. Malik ◽  
R. Sinhasan ◽  
D. V. Singh
Keyword(s):  
Journal Bearing ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Tilting Pad ◽  
The Comparative Study ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings ◽  
Theoretical Performance

The rolling-pad journal bearing is a kinematic variation of the well-known tilting-pad journal bearing. In rolling-pad bearings, the pads, instead of tilting about fixed pivots, roll at their back surfaces on the inside surface of a common sleeve to accommodate changes in the operating conditions of the bearing. This paper presents a comparison of the theoretical performance characteristics of rolling-pad journal bearings with those of tilting-pad journal bearings. The comparative study indicates that the dynamic performance characteristics of the rolling-pad bearing configuration are superior to those of the tilting-pad bearing.

Linking Rigid and Flexible Multibody Systems via Thin Fluid Films Actively Controlled

2008 ◽  
Author(s):  
Edgar A. Estupinan ◽  
Ilmar F. Santos
Keyword(s):  
Film Thickness ◽  
Multibody Systems ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Fluid Film ◽  
Fluid Films ◽  
Thin Fluid ◽  
Dynamically Loaded ◽  
Reaction Forces ◽  
Fluid Film Thickness

This work describes in details the steps involved within the mathematical modelling of multibody systems (rigid and flexible) interconnected via controllable thin fluid films. The dynamics of the mechanical components are described with help of multibody dynamics and finite element method. In this paper, the methodology is applied to reciprocating machines such as hermetic reciprocating compressors and internal combustion engines. In previous studies [1], it has been shown that for a light duty vehicle, the friction losses may reach until 48% of the total energy consumption of an engine and from that, almost 30% are coming from bearings and crankshaft. Therefore, considering that the dynamics of the fluid films in the journal bearings can be actively controlled by means of different types of actuators, allowing significant reduction of wear and vibrations, one of the aims of this paper is to study the feasibility of applying active lubrication to the main journal bearings of reciprocating machines. In this framework the paper gives a theoretical contribution to the combined fields of fluid-structure interaction and active vibration control. The hydrodynamic pressure distribution for an active lubricated finite journal bearing dynamically loaded can be calculated by numerically solving the modified Reynold’s equation [2], by means of finite-difference method and integrated over the pressure area in order to obtain the dynamic reaction forces among components. These forces are strongly nonlinear and dependent on the relative kinematics of the system. From the point of view of active lubrication and specifically considered the case of a dynamically loaded journal bearing, the injection pressure should be controlled in the time domain. However, taking into account that the pressures and reaction forces in a reciprocating machine have a cyclic behaviour, the fluid film thickness of the main bearings may be modified by controlling the oil pressure injection, depending on the crank angle and the load bearing condition. It can be mentioned that the pressure and flow may be controlled by mechanical cam systems, piezoelectric nozzles [3] [4] or servovalves [5] [6], therefore, an adequate control strategy has to be defined. The fluid film forces are coupled to the set of nonlinear equations that describes the dynamics of the mechanical system. Such a set of equations is numerically solved giving some insights into the following parameters: a) maximum fluid film pressure, b) minimum fluid film thickness, c) maximum vibration levels and d) viscous frictional forces. The behaviour of such parameters is investigated when the system operate with conventional hydro-dynamic lubrication, passive hybrid lubrication and controlled hybrid lubrication.

Elastohydrodynamic analysis of double-layered journal bearings lubricated with couple-stress fluids

2005 ◽  
Vol 219 (2) ◽  
pp. 145-165 ◽  
Author(s):  
M Lahmar
Keyword(s):  
Couple Stress ◽  
Journal Bearing ◽  
Perturbation Technique ◽  
Dynamic Performance ◽  
Performance Characteristics ◽  
Transient Pressure ◽  
Variable Theory ◽  
Stress Parameter ◽  
Linear Elastostatics ◽  
Bearing System

Elastohydrodynamic (EHD) analysis of a journal bearing with a realistic model for the bearing made of two distinct layers is extended to include couple-stress effects in lubricants blended with polymer additives. Based on the Stokes microcontinuum theory, a transient pressure differential equation (modified Reynolds' equation) is derived from the fluid motion equations and solved numerically. The elegant and powerful semi-analytical approach based on the complex variable theory developed in an earlier work is extended to solve linear elastostatics problems for a double-layered journal bearing. The EHD solution in isothermal conditions is obtained numerically by means of an iterative procedure. By the finite perturbation technique, the eight fluid-film stiffness and damping coefficients are determined. At the threshold of instability, the dynamic coefficients are used as input data for studying the linear stability of the rotor-bearing system. According to the results obtained, the influence of couple-stress parameter on the static and dynamic performance characteristics of the compliant journal-bearing system is physically apparent and not negligible. Compared with the Newtonian lubricants case, lubricants with couple-stresses provide an increase in the load-carrying capacity and stability, a reduction in the attitude angle and the friction factor. It is also found that the fluid-solid interaction effect on the performance characteristics is more important, especially for high values of couple-stress parameter and relative rigidity of liner-bush assembly.

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