Closure to “Discussions of ‘Static and Dynamic Performance of Externally Pressurized Fluid Film Journal Bearings in the Turbulent Regime’” (1974, ASME J. Lubr. Technol., 96, p. 390)

1974 ◽  
Vol 96 (3) ◽  
pp. 390-390
Author(s):  
S. Heller
Keyword(s):  
Dynamic Performance ◽  
Journal Bearings ◽  
Fluid Film ◽  
Turbulent Regime

Thermohydrodynamic Analysis of Process-Liquid Hydrostatic Journal Bearings in Turbulent Regime, Part I: The Model and Perturbation Analysis

1995 ◽  
Vol 62 (3) ◽  
pp. 674-678 ◽  
Author(s):  
Zhou Yang ◽  
L. San Andres ◽  
D. W. Childs
Keyword(s):  
Energy Equation ◽  
Dynamic Performance ◽  
Journal Bearings ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Fluid Inertia ◽  
Flow Process ◽  
Fluid Film Bearings ◽  
Friction Factors ◽  
Flow Turbulence

A bulk-flow thermohydrodynamic (THD) analysis is developed for prediction of the static and dynamic performance characteristics of turbulent-flow, process-liquid, hydrostatic journal bearings (HJBs). Pointwise evaluation of temperature and hence liquid properties is achieved through the solution of the energy equation in the fluid film with insulated boundaries, and justified for fluid film bearings with external pressurization. Fluid inertia within the film lands and at recess edges is preserved in the analysis. Flow turbulence is accounted through turbulence shear parameters based on friction factors derived from Moody’s formulae. The effects of fluid compressibility and temperature variation in the bearing recesses are included. Numerical solution and results are presented in the second part of this work and compared with some limited experimental data for a liquid hydrogen (LH2) bearing.

Effects of Turbulence and Viscosity Variation on the Dynamic Coefficients of Fluid Film Journal Bearings

1985 ◽  
Vol 107 (2) ◽  
pp. 256-261 ◽  
Author(s):  
D. F. Wilcock ◽  
O. Pinkus
Keyword(s):  
High Speed ◽  
Dynamic Stiffness ◽  
Journal Bearings ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Dynamic Coefficients ◽  
Damping Characteristics ◽  
Fluid Film Bearings ◽  
Viscosity Variation ◽  
Stiffness And Damping

Many high-speed or large fluid film bearings operate in the turbulent regime. However, relatively little consideration has been given to the effects of turbulence and of the variation in viscosity on the dynamic stiffness and damping characteristics of the bearings. Since the dynamic behavior of the rotor supported on such bearings is often closely tied to the bearing dynamic coefficients, knowledge of them may be critical to both the design and the in-place correction of rotor instabilities. These effects are here considered in some detail on the basis of computer calculated analytical results, both in general dimensionless terms and with regard to a specific numerical example.

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.

Analysis of Plain Cylindrical Journal Bearings in Turbulent Regime

1964 ◽  
Vol 86 (2) ◽  
pp. 387-394 ◽  
Author(s):  
E. B. Arwas ◽  
B. Sternlicht ◽  
R. J. Wernick
Keyword(s):  
Carrying Capacity ◽  
Correlation Factor ◽  
Journal Bearings ◽  
Fluid Film ◽  
Published Data ◽  
Turbulent Regime ◽  
Load Carrying Capacity ◽  
Steady State Analysis ◽  
Load Carrying ◽  
Film Stiffness

This paper presents a simplified steady-state analysis of turbulent lubrication. Load-carrying capacity, attitude angle, and fluid film stiffness for plain cylindrical journal bearings operating in the turbulent regime are presented. Simple, easy to use relations for the calculation of load-carrying capacity were generated. Fluid film stiffnesses are included so that they can be used to calculate system critical speeds. In the analysis presented here, side leakage is neglected; however, existing published data on a 360 deg plain circular bearing were used to establish a correlation factor between laminar and turbulent leakage factors.

Self-Centering Film Dividers

1980 ◽  
Vol 102 (4) ◽  
pp. 490-494
Author(s):  
D. F. Wilcock
Keyword(s):  
Reynolds Number ◽  
High Speed ◽  
Journal Bearings ◽  
The Self ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Frictional Drag ◽  
Thrust Bearings ◽  
Average Shear ◽  
Effective Reynolds Number

One rather effective way to reduce the frictional drag of fluid film journal or thrust bearings, when operating in the turbulent regime, is to introduce a “floating” member dividing the fluid film into two roughly equal parts. The average shear rate is unchanged, but the effective Reynolds number is reduced, with a corresponding reduction in friction power. Such dividers have been widely used in floating sleeve journal bearings of the small high speed type. Use in thrust bearings is not known. In either application, it is essential that the self-centering divider center itself under all conditions after shaft rotation is initiated. This paper describes and analyzes a divider design that has such a property.

A Theoretical Estimation of the Performance of Journal Bearings Operating in the Turbulent Lubrication Regime

1975 ◽  
Vol 17 (2) ◽  
pp. 52-56 ◽  
Author(s):  
K. F. King ◽  
C. M. Taylor
Keyword(s):  
Kinematic Viscosity ◽  
Journal Bearings ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Theoretical Estimation ◽  
Theoretical Evaluation ◽  
Fluid Film Bearings ◽  
Lubrication Regime

The use of process fluids of low kinematic viscosity as lubricants and the ever increasing surface speeds which are being encountered in fluid-film bearings have meant an increase in the number of bearings which operate in the turbulent regime. This paper describes a theoretical evaluation of the performance of 360-degree journal bearings operating turbulently, presents generalized data and discusses the results with comments upon the assumptions made and practical realities.

Static and Dynamic Performance of Externally Pressurized Fluid Film Journal Bearings in the Turbulent Regime

1974 ◽  
Vol 96 (3) ◽  
pp. 381-389 ◽  
Author(s):  
S. Heller
Keyword(s):  
Load Capacity ◽  
Dynamic Performance ◽  
Dynamic Test ◽  
Axial Flow ◽  
Reynolds Numbers ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Inertia Effects ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The fluid film lubrication equations for externally pressurized bearings are solved for steady-state performance and spring and damping coefficients using finite differences and a variable grid bearing model. Turbulence is included as local effective viscosities. Entrance inertia effects are included at the recess edges and are seen to be a significant factor for flow estimates. Performance data is developed for a six-pocket bearing of L/D = 0.75. Experimental verification was obtained for load capacity, flow, and dynamic coefficients, using a two-bearing dynamic test rig and water at speeds from 0 to 4000 rpm. Axial flow of Reynolds numbers range from 22,000 to 125,000.

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