A Study of Orifice Compensated Multilobe Hole-Entry Hybrid Journal Bearing

2007 ◽  
Author(s):  
T. Nagaraju ◽  
J. Sharana Basavaraja ◽  
Satish C. Sharma ◽  
S. C. Jain
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Academic Community ◽  
Flow Through ◽  
Direct Stiffness ◽  
Improved Performance ◽  
The Stability ◽  
Offset Factor ◽  
Bearing System

The hydrostatic and hybrid journal bearings are finding increasing applications due to their excellent characteristics. The non-recessed hydrostatic/hybrid journal bearings have been developed so to provide an improved performance over the recessed/pocketed hydrostatic/hybrid journal bearings. The stability and unsteady behavior of the journal bearings is greatly influenced by bearing geometry, and accordingly various designs have been used by designers to achieve the desired objective. The non-circular journal bearings i.e. the multilobe journal bearing exhibits better stability as well as a superior capability to suppress whirl. In the present paper a theoretical study pertaining to a novel journal bearing configuration i.e. two-lobe hole-entry hybrid journal bearing is being presented. The work presented in this paper aims to study the performance of a two-lobe hole-entry hybrid journal bearing system compensated by a orifice restrictors. The Reynolds equation governing the flow of lubricant in the clearance space between the journal and bearing together with the equation of flow through an orifice restrictor has been solved using FEM and Galerkin’s method. The bearing performance characteristics results have been simulated for an orifice compensated non-recessed two-lobe hole-entry hybrid journal bearing symmetric configuration for the various values of offset factor (δ), restrictor design parameter (cS2) and the value external load (Wo). Further, a comparative study of the performance of a two-lobe non-recessed hole-entry hybrid journal bearing system vis a vis circular hole-entry symmetric hybrid journal bearing system have also been carried out so that a designer has a better flexibility in choosing a suitable bearing configuration. The simulated numerical results for the non-recessed two-lobe symmetric hole-entry hybrid journal bearing system with an offset factor (δ) greater than one indicates a significant improvement of the order of 30 to 50 percent in the values of direct stiffness and direct damping coefficients as compared to a circular symmetric hole entry hybrid journal bearing system. The results presented in the paper are expected to be quite useful to the bearing designers as well as for the academic community.

scholarly journals Performance of an Orifice Compensated Two-Lobe Hole-Entry Hybrid Journal Bearing

2008 ◽  
Vol 2008 ◽  
pp. 1-10 ◽  
Author(s):  
J. Sharana Basavaraja ◽  
Satish C. Sharma ◽  
S. C. Jain
Keyword(s):  
External Load ◽  
Design Parameter ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Damping Coefficients ◽  
Symmetric Configuration ◽  
Flow Through ◽  
Direct Stiffness ◽  
Offset Factor ◽  
Bearing System

The work presented in this paper aims to study the performance of a two-lobe hole-entry hybrid journal bearing system compensated by orifice restrictors. The Reynolds equation governing the flow of lubricant in the clearance space between the journal and bearing together with the equation of flow through an orifice restrictor has been solved using FEM and Galerkin's method. The bearing performance characteristics results have been simulated for an orifice compensated nonrecessed two-lobe hole-entry hybrid journal bearing symmetric configuration for the various values of offset factor , restrictor design parameter , and the value of external load . Further, a comparative study of the performance of a two-lobe hole-entry hybrid journal bearing system with a circular hole-entry symmetric hybrid journal bearing system has also been carried out so that a designer has a better flexibility in choosing a suitable bearing configuration. The simulated numerical results indicate that for the two-lobe symmetric hole-entry hybrid journal bearing system with an offset factor greater than one provides 30 to 50 percent larger values of direct stiffness and direct damping coefficients as compared to a circular symmetric hole-entry hybrid journal bearing system.

Dynamic stability of micropolar lubricated hydrodynamic offset-halves journal bearings

2020 ◽  
pp. 135065012093685
Author(s):  
Sanyam Sharma ◽  
Chimata M Krishna
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Critical Mass ◽  
Journal Bearings ◽  
Aspect Ratios ◽  
Input Parameters ◽  
Output Characteristics ◽  
The Stability ◽  
Offset Factor

The plain circular journal bearings are not found to be stable by researchers when used in high speed rotating machineries. Hence, extensive research in the study of stability characteristics of non-circular bearings or lobed bearings assumed importance, of late. Present article deals with the stability analysis of non-circular offset bearing by taking selected set of input and output parameters. Modified Reynolds equation for micropolar lubricated rigid journal bearing system is solved using finite element method. Two kinds of input parameters namely, offset factors (0.2, 0.4) and aspect ratios (1.6, 2.0) have been selected for the study. The important output characteristics such as load, critical mass, whirl frequency ratio, and threshold speed are computed and plotted for various set of values of input parameters. The results obtained indicate that micropolar lubricated circular offset bearing is highly stable for higher offset factor and higher aspect ratio.

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.

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.

Stability analysis of a rigid rotor supported by two-lobe hydrodynamic journal bearings operating with a non-Newtonian lubricant

2018 ◽  
Vol 233 (6) ◽  
pp. 884-898 ◽  
Author(s):  
Saurabh K Yadav ◽  
Arvind K Rajput ◽  
Nathi Ram ◽  
Satish C Sharma
Keyword(s):  
Reynolds Equation ◽  
Pressure Field ◽  
Equation Of Motion ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Linear Finite Element ◽  
Runge Kutta Method ◽  
The Stability ◽  
Ellipticity Ratio ◽  
Bearing System

In the present work, an investigation has been performed on a rigid rotor supported by two-lobe journal bearings operating with a non-Newtonian lubricant. The governing Reynolds equation for pressure field is solved by using non-linear finite element method. Further to study the dynamic stability of the bearing system, governing equation of motion for the rotor position is solved by fourth order Runge–Kutta method. Bifurcation and Poincaré maps of two-lobe bearings are presented for different values of the non-Newtonian parameter and bearing ellipticity ratio. The numerical results illustrate that the ellipticity of a bearing with a dilatant lubricant improve the stability of the rotordynamic system.

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

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
H. C. Garg ◽  
Vijay Kumar ◽  
H. B. Sharda
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Journal Bearing ◽  
Flow Equation ◽  
Journal Bearings ◽  
Constant Flow ◽  
Viscosity Variation ◽  
Bearing System ◽  
Flow Valve ◽  
Newtonian Behavior

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.

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.

The effect of active control on stability characteristics of hydrodynamic journal bearings with an axial groove

2002 ◽  
Vol 216 (9) ◽  
pp. 939-946 ◽  
Author(s):  
B-H Rho ◽  
K-W Kim
Keyword(s):  
Active Control ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Linear Dynamic ◽  
Conventional Analysis ◽  
Theoretical Investigations ◽  
Rotor Bearing ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Bearing System

Results of theoretical investigations on stability characteristics of an actively controlled hydrodynamic journal bearing are presented. Proportional, derivative and integral controls are adopted for a hydrodynamic journal bearing with an axial groove. Furthermore, a cavitation algorithm, implementing the Jakobsson-Floberg-Olsson boundary condition, is adopted to predict cavitation regions in a fluid film more accurately than the conventional analysis, which uses the Reynolds condition. Using the bearing's linear dynamic coefficients, which are evaluated from the perturbation method, the stability characteristics of a rotor-bearing system are investigated using the Routh-Hurwitz criteria. It is shown that the instability threshold speed of a rotor-bearing system can be greatly increased and the unbalanced responses of the system can be markedly decreased by both proportional and derivative control of the bearing. Results show that active control of a hydrodynamic journal bearing can be adopted for stability improvement and reduction of the unbalanced whirl amplitude of a rotor-bearing system.

Influence of surface textures on the dynamic stability and performance parameters of hydrodynamic two-lobe journal bearings

2021 ◽  
pp. 135065012110700
Author(s):  
Niranjan Singh ◽  
R K Awasthi
Keyword(s):  
Dynamic Stability ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Surface Texturing ◽  
Journal Bearings ◽  
Performance Parameters ◽  
Surface Textures ◽  
And Performance ◽  
The Impact ◽  
Bearing System

Surface texturing can improve the performance of journal bearing system. The present study theoretically investigates the impact of surface textures on the dynamic stability and performance parameters of two-lobe journal bearing system. Galerkin's finite element method is used to solve the Reynolds equation governing the flow of lubricant in the gap between the bearing and the journal. Reynolds boundary conditions are applied in the simulation study of plain, full-textured, partially textured-I and partially textured-II configurations of two-lobe journal bearing. The dynamic stability and performance parameters of textured two-lobe journal bearings are computed with the variation of eccentricity ratio and dimple depth and compared with circular bearing results. The results indicate that the existence of surface textures in the pressure build-up zone ranging from 126°–286° and at unity dimple aspect ratio can significantly improve the dynamic stability and performance parameters of two-lobe bearing system.

scholarly journals Transformation between polar and rectangular coordinates of stiffness and dampness parameters in hydrodynamic journal bearings

Friction ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 201-206 ◽  
Author(s):  
Zhuxin Tian ◽  
Yu Huang
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Stability Boundary ◽  
Journal Bearings ◽  
Polar Coordinates ◽  
Oil Film ◽  
Rectangular Coordinates ◽  
Bearing Stiffness ◽  
The Stability

Abstract The stiffness and dampness parameters of journal bearings are required in rectangular coordinates for analyzing the stability boundary and threshold speed of oil film bearings. On solving the Reynolds equation, the oil film force is always obtained in polar coordinates; thus, the stiffness and dampness parameters can be easily obtained in polar coordinates. Therefore, the transformation between the polar and rectangular coordinates of journal bearing stiffness and dampness parameters is discussed in this study.

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