Analysis of Hybrid (Hydrodynamic/Hydrostatic) Journal Bearing

2013 ◽  
Vol 650 ◽  
pp. 385-390 ◽  
Author(s):  
Vijay Kumar Dwivedi ◽  
Satish Chand ◽  
K.N. Pandey
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Gas Turbines ◽  
High Speed ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Natural Boundary Condition ◽  
Dimensional Solution

The Hybrid (hydrodynamic/ hydrostatic) journal bearing system has found wide spread application in high speed rotating machines such as compressors, gas turbines, steam turbines, etc. The present studies include solution of Reynolds equation for hydrodynamic journal bearing with infinitely long approximation (ILA), infinitely short bearing approximation (ISA) and finite journal bearing approximation. Further Finite Journal bearing approximation considers two dimensional solution of Reynolds equation with natural boundary condition, which cannot be solved by analytical method. So, here the solutions for finite journal bearing have been done with finite difference method (a MATLAB® code is prepared for finite difference method) to get bearing performance parameters such as load capacity, Sommerfeld no., etc.

Effect of Turbulence and Offset Loading on the Performance of a Single Pad Externally Adjustable Fluid Film Bearing

2012 ◽  
Author(s):  
B. Satish Shenoy ◽  
Rammohan S. Pai B. ◽  
Raghuvir Pai B. ◽  
Shrikanth Rao D.
Keyword(s):  
Steady State ◽  
Finite Difference ◽  
Aspect Ratio ◽  
Finite Difference Method ◽  
Difference Method ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Fluid Film ◽  
Wide Range ◽  
Steady State Performance

Paper deals with the effect of turbulence on steady state performance characteristics of an eccentrically loaded 120° single pad externally adjustable fluid film bearing. The bearing has an aspect ratio of one and operates over a wide range of eccentricity ratios and adjustments. Two load-offset positions (β/χ) of 0.45 and 0.55 are considered in the present analysis. Reynolds equation incorporated with the Linearized turbulence model of Ng and Pan is solved numerically using finite difference method. A comparative study predicts that, load capacity of a bearing operating with β/χ = 0.55 and Re = 16000 is superior for negative radial and tilt adjustment configuration of the pad.

scholarly journals Numerical analysis on the performance characteristics of a new gas journal bearing by using finite difference method

2021 ◽  
Vol 13 (6) ◽  
pp. 168781402110280
Author(s):  
Yuntang Li ◽  
Ruirui Li ◽  
Yueliang Ye ◽  
Xiaolu Li ◽  
Yuan Chen
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Journal Bearing ◽  
Load Capacity ◽  
Linear Perturbation ◽  
Eccentricity Ratio ◽  
Dynamic Performances ◽  
The Stability ◽  
Gas Journal Bearing

This paper proposes a novel gas journal bearing in which orifices are different in diameter and distribute unevenly. Finite Difference Method (FDM) combined with Linear Perturbation Method (LPM) is used to solve the unsteady-state Reynolds equation of the flow field in the bearing clearance. Moreover, four types of bearing structures are used to discuss the effects of orifices different in diameter and uneven distribution on the bearing performance. The results demonstrate that the new bearing has better static and dynamic performances compared with those of traditional bearing in which orifices are equal in diameter and distribute evenly. Moreover, thin gas film thickness, high supply pressure, and large eccentricity ratio are hopeful for improving load capacity of the new bearing. Furthermore, the stability of the novel bearing is improved if eccentricity ratio is 0.25–0.3.

The effect of turbulence on the performance of a two-lobe journal bearing lubricated with a couple stress fluid

2016 ◽  
Vol 68 (3) ◽  
pp. 336-340 ◽  
Author(s):  
Boualem Chetti
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Couple Stress ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Couple Stress Fluid ◽  
Turbulent Regime ◽  
Content Type ◽  
Couple Stress Fluids

Purpose This paper presents an analysis of the static characteristics of two-lobe journal bearings lubricated with couple stress fluids operating in a turbulent regime. The modified Reynolds equation for a couple stress fluids taking into consideration the effect of turbulence is solved using finite difference method. The load-carrying capacity, attitude angle, friction coefficient and side leakage are determined for various values of the couple stress parameter and Reynolds number. It is found that the couple stress fluids affect significantly on the performance of a two-lobe journal bearing in laminar and turbulent regime. Design/methodology/approach The modified Reynolds equation for a couple stress fluids taking into consideration the effect of turbulence is solved using finite difference method. Findings It is found that the couple stress fluids affect significantly on the performance of a two-lobe journal bearing in laminar and turbulent regime. Originality/value A couple stress fluid is used for lubrication of a two-lobe journal bearing in turbulent regime and laminar.

Analysis of Infinitely Short and Infinitely Long Hydrodynamic Journal Bearings Under Micro-Polar Fluid by Direct Integration Method

2017 ◽  
Author(s):  
Bikash Routh
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Integration Method ◽  
Pressure Profile ◽  
Journal Bearings ◽  
Direct Integration ◽  
Polar Fluid ◽  
Direct Integration Method

In the present paper Reynolds equation of lubrication under micro-polar fluid for journal bearing is solved by direct-integration method under infinitely long and infinitely short journal bearing assumptions [1]. Infinitely long-bearing and infinitely short bearing solutions are the two available approximate closed form solutions for journal bearings. In the present investigation, solution of Reynolds equation i.e. pressure profile is compared with pressure profile obtained by previously used approximate method like finite difference method (FDM). Mentionable here that any approximation method needs lots of calculation and computer programing to get the result. In the present work it has been found that direct-integration method leads the almost same result as the conventionally used complex finite difference method. CFD analysis is also presented in the present work to justify the profile obtained by direct numerical method. It has seen here that theoretical and simulation results are in good agreement to each other’s.

Combined Influence of Misalignment and Orifice Diameter on the Static Performances of Hydrostatic, Water-Lubricated Journal Bearings

2014 ◽  
Vol 607 ◽  
pp. 608-611
Author(s):  
Hui Hui Feng ◽  
Chun Dong Xu ◽  
Feng Feng Wang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Film Thickness ◽  
Power Loss ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Orifice Diameter ◽  
Rigid Rotor ◽  
Static Performance

The water-lubricated bearings have gained an increasing focus to overcome the disadvantages of the oil film bearings and gas bearings. In this paper, the influences of orifice diameter in aligned and misaligned conditions on the static performance of two hydrostatic, four-recess, water-lubricated journal bearings used to support a rigid rotor, are investigated. The steady Reynolds equation for the journal bearing for the turbulent bulk flow and the film thickness expression considering tilting angles are used and numerically solved by finite difference method. Results demonstrate that the static performances, such as the quality, power loss and temperature rise are affected by the tilting angles, orifice diameter to some degree.

Averaging effect on pitch errors in hydrostatic lead screws considering helical recess layout and nut misalignment

2017 ◽  
Vol 232 (9) ◽  
pp. 1181-1192
Author(s):  
Yongtao Zhang ◽  
Changhou Lu ◽  
Yunpeng Liu
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Radial Displacement ◽  
Continuity Equation ◽  
Reynolds Equation ◽  
Spatial Frequencies ◽  
The Finite Difference Method ◽  
Low Speeds ◽  
Flank Surface

The hydrostatic nut usually has different helical recess layouts and the nut misalignment (including radial displacement and tilt) may occur during movement, which will influence the averaging effect on pitch errors, i.e. the motion accuracy of the hydrostatic nut. This paper researches the averaging effect on pitch errors in capillary compensated hydrostatic lead screws, under low speeds and considering the helical recess layout and the nut misalignment. Based on the equivalent plane of the flank surface of threads, whose normal clearance is calculated by vector operations, the Reynolds equation and the flow continuity equation are solved using the finite difference method. The results show that (a) the averaging coefficient presents bulges at corresponding spatial frequencies for the hydrostatic nut with discontinuous helical recesses, (b) the positions of the first and second periodical fluctuations of the averaging coefficient are the same for the hydrostatic nut with symmetric continuous helical recesses, symmetric discontinuous helical recesses, or asymmetric continuous helical recesses, and (c) The nut misalignment has little influence on the averaging coefficient.

Accuracy analysis of narrow groove theory for spiral grooved gas seals: A comparative study with numerical solution of Reynolds equation

2018 ◽  
Vol 233 (6) ◽  
pp. 899-910
Author(s):  
Wanjun Xu ◽  
Jiangang Yang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Reynolds Equation ◽  
Compressible Fluids ◽  
Accuracy Analysis ◽  
Performance Parameters ◽  
Typical Performance ◽  
Gas Seals ◽  
Film Stiffness

This study examined the accuracy of narrow groove theory for spiral grooved gas seals. Designed for compressible fluids, a finite difference method was proposed to solve the two-dimensional compressible Reynolds equation. The predictions of narrow groove theory were compared with those of the Reynolds equation. The typical performance parameters including gas film force, leakage, gas film stiffness, and torque were analyzed. The results show that the predictions of narrow groove theory generally agree with those of finite difference method when the number of grooves is more than eight. The gas film force, leakage, and gas film stiffness were slightly overestimated by narrow groove theory, with better accuracy for gas film force, leakage, and torque than for gas film stiffness. Although some cases showed deviation for gas film stiffness of as much as 52%, most deviations can be effectively ignored. Therefore, it is feasible to use narrow groove theory for qualitative analysis such as groove shape optimization. The present analysis provides the optimum groove parameters for the investigated seal.

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