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

2004 ◽  
Vol 126 (3) ◽  
pp. 630-634 ◽  
Author(s):  
Vijay Kumar ◽  
Satish C. Sharma and ◽  
S. C. Jain
Keyword(s):  
Temperature Rise ◽  
Journal Bearing ◽  
Stability Margin ◽  
Fluid Film ◽  
Elasticity Equations ◽  
Fluid Film Thickness ◽  
The Stability ◽  
Coupled Solution ◽  
Bearing System ◽  
Selection Of

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.

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

2018 ◽  
Vol 233 (1) ◽  
pp. 350-368 ◽  
Author(s):  
Kamal Budheeja ◽  
Suresh Verma
Keyword(s):  
Micropolar Fluid ◽  
Journal Bearing ◽  
Stability Margin ◽  
Constant Flow ◽  
Micropolar Fluids ◽  
Stability Point ◽  
Nonlinear Transient ◽  
The Stability ◽  
Bearing System ◽  
Flow Valve

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.

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

2005 ◽  
Vol 48 (1) ◽  
pp. 140-146 ◽  
Author(s):  
T. Nagaraju ◽  
Satish C. Sharma ◽  
S. C. Jain
Keyword(s):  
Journal Bearing ◽  
Stability Margin ◽  
The Stability ◽  
Bearing System

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.

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.

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 wear on the performance of hole-entry hybrid misaligned journal bearing in turbulent regime

2014 ◽  
Vol 66 (4) ◽  
pp. 509-519 ◽  
Author(s):  
Nathi Ram ◽  
Satish C. Sharma
Keyword(s):  
Film Thickness ◽  
Design Parameter ◽  
Journal Bearing ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Laminar Regime ◽  
Content Type ◽  
Fluid Film Thickness ◽  
System Operating ◽  
Bearing System

Purpose – The present work aimed to study analytically the influence of wear on the performance of a capillary-compensated hole-entry hybrid misaligned journal bearing system operating in a turbulent regime. The numerically simulated results are presented for the chosen values of restrictor design parameter, Reynolds numbers, wear depth and misalignment parameters. Design/methodology/approach – The wear caused on the bearing surface due to start/stop operations is modeled using the Dufrane’s abrasive wear model. The modified Reynolds equation based on Constantinescu’s lubrication theory is solved using finite element method together with capillary restrictor flow equation. Findings – It is found that the value of minimum fluid-film thickness increases significantly for a constant value of restrictor design parameter when unworn aligned bearing operates in turbulent regime vis-à-vis laminar regime. Further, it has also been observed that when a worn bearing operates in laminar/turbulent regimes, the reduction in the value of minimum fluid-film thickness is more due to journal misalignment as compared to the aligned bearing operates in laminar regime. Originality/value – The present work is original concerning the performance of worn hole-entry hybrid misaligned journal bearing system operating in turbulent regime. The results are expected to be quite useful for the bearing designer.

Non-linear stability analysis of micropolar fluid lubricated journal bearings with turbulent effect

2019 ◽  
Vol 71 (1) ◽  
pp. 31-39
Author(s):  
Subrata Das ◽  
Sisir Kumar Guha
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Micropolar Fluid ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Content Type ◽  
Non Linear ◽  
The Stability ◽  
Bearing System

Purpose The purpose of this paper is to investigate the effect of turbulence on the stability characteristics of finite hydrodynamic journal bearing lubricated with micropolar fluid. Design/methodology/approach The non-dimensional transient Reynolds equation has been solved to obtain the non-dimensional pressure field which in turn used to obtain the load carrying capacity of the bearing. The second-order equations of motion applicable for journal bearing system have been solved using fourth-order Runge–Kutta method to obtain the stability characteristics. Findings It has been observed that turbulence has adverse effect on stability and the whirl ratio at laminar flow condition has the lowest value. Practical implications The paper provides the stability characteristics of the finite journal bearing lubricated with micropolar fluid operating in turbulent regime which is very common in practical applications. Originality/value Non-linear stability analysis of micropolar fluid lubricated journal bearing operating in turbulent regime has not been reported in literatures so far. This paper is an effort to address the problem of non-linear stability of journal bearings under micropolar lubrication with turbulent effect. The results obtained provide useful information for designing the journal bearing system for high speed applications.

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.

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