Performance Analysis of Grease-Lubricated Journal Bearings Including Thermal Effects

1997 ◽  
Vol 119 (4) ◽  
pp. 859-868 ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Performance Analysis ◽  
Thermal Effects ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Journal Bearings ◽  
Computational Results ◽  
Governing Equations ◽  
Bingham Plastic ◽  
The Ideal

A detailed analysis of the flow characteristics and lubrication effectiveness of grease in journal bearings is presented. Based on the ideal Bingham plastic model, the appropriate governing equations are developed which effectively handle the formation of a floating core as well as a core which may attach itself to either the shaft or the stationary bushing. The formulation and numerical solutions presented pertain to three-dimensional flows in finite journal bearings. Moreover, an extensive amount of computational results are presented, which take thermal effects into account according to the thermohydrodynamic theory.

Investigation of the micropolar lubricant and thermal effects in the slot entry hybrid journal bearings

2017 ◽  
Vol 232 (11) ◽  
pp. 2103-2116 ◽  
Author(s):  
Pankaj Khatak ◽  
HC Garg
Keyword(s):  
Performance Analysis ◽  
Present Article ◽  
Thermal Effects ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Reliable Performance ◽  
Isothermal Characteristics

The present article studies the combined influence of the micropolar lubricant and thermal effects in the slot entry hybrid journal bearings. Bearing performance characteristics are computed by the concurrent solution of modified Reynolds, three-dimensional micropolar energy, and three-dimensional conduction equations. Thermohydrostatic characteristics of the slot entry hybrid journal bearings have been studied vis-à-vis isothermal characteristics. The results obtained numerically indicate that isoviscous assumption of the lubricant is incorrect and the bearing performance is significantly affected by the increase in temperature. Hence, it is essential to consider the thermal effects for the bearings operating with the micropolar lubricant for reliable performance analysis of the bearings.

A Contribution to the Analysis of the Thermo-Hydrodynamic Lubrication of Porous Self-Lubricating Journal Bearings

2010 ◽  
Vol 297-301 ◽  
pp. 618-623 ◽  
Author(s):  
S. Boubendir ◽  
Salah Larbi ◽  
Rachid Bennacer
Keyword(s):  
Thermal Effects ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Governing Equations ◽  
Hydrodynamic Analysis ◽  
Result Show

In this work the influence of thermal effects on the performance of a finite porous journal bearing has been investigated using a thermo-hydrodynamic analysis. The Reynolds equation of thin viscous films is modified taking into account the oil leakage into the porous matrix, by applying Darcy’s law to determine the fluid flow in the porous media. The governing equations were solved numerically using the finite difference approach. Obtained result show a reduction in the performance of journal bearings when the thermal effects are accounted for and, this reduction is greater when the load capacity is significant.

3D Numerical Simulation of the Airflow in a Pneumatic Splicer

2011 ◽  
Vol 130-134 ◽  
pp. 2345-2348
Author(s):  
Xiao Xing ◽  
Guo Ming Ye
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Air Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Swirling Flows ◽  
Computational Results ◽  
Cfd Model ◽  
3D Numerical Simulation ◽  
Computational Fluid Dynamics Cfd

To investigate the effect of air flow in an pneumatic splicer on splicing performance, a computational fluid dynamics (CFD) model has been developed to simulate the air flow characteristics in an splicing chamber. Three-dimensional numerical simulation is conducted and standard K-ε turbulence model is used. Velocity distributions in the chamber are presented and analyzed. The computational results show that the velocities in the chamber are transonic. The air flows in the chamber are two swirling flows with opposite directions. This work also shows that CFD technique can provide a better understanding of the behavior of the high speed air flow in the air splicing chamber.

Thermoelastohydrodynamic behavior of misaligned plain journal bearings

2013 ◽  
Vol 227 (11) ◽  
pp. 2582-2599 ◽  
Author(s):  
ZS Zhang ◽  
XD Dai ◽  
YB Xie
Keyword(s):  
Thermal Effects ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Misalignment Angle ◽  
Synthetic Solution ◽  
Simulation Results ◽  
Generalized Reynolds Equation

Under severe operating conditions, the thermal effects and various deformations play an important role in determining the performance of misaligned plain journal bearings. However, the thermal effects and various deformations are rarely considered simultaneously in most studies on the misaligned plain journal bearings. In this article, a comprehensive thermoelastohydrodynamic model of the misaligned plain journal bearings is developed that involves the synthetic solution of the generalized Reynolds equation, three-dimensional energy equation, and heat conduction equations of the solids. Based on this model, series of simulation results are provided to examine the influence of the thermal effects and deformations on the behavior of the misaligned plain journal bearings. In addition, the comparisons between the thermohydrodynamic and complete thermoelastohydrodynamic model are also presented for different misalignment angle and magnitude. Results show that the thermal effects and various deformations should not be ignored because of their significant influence on the film thickness, film pressure as well as other bearings characteristics.

Numerical Simulations of Three-Dimensional Flows in a Cubic Cavity With an Oscillating Lid

1993 ◽  
Vol 115 (4) ◽  
pp. 680-686 ◽  
Author(s):  
Reima Iwatsu ◽  
Jae Min Hyun ◽  
Kunio Kuwahara
Keyword(s):  
Numerical Solutions ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Time Dependent ◽  
Navier Stokes ◽  
Physical Parameters ◽  
Navier Stokes Equations ◽  
Sinusoidal Oscillations ◽  
Dependent Flow

Numerical studies are made of three-dimensional flow of a viscous fluid in a cubical container. The flow is driven by the top sliding wall, which executes sinusoidal oscillations. Numerical solutions are acquired by solving the time-dependent, three-dimensional incompressible Navier-Stokes equations by employing very fine meshes. Results are presented for wide ranges of two principal physical parameters, i.e., the Reynolds number, Re ≤ 2000 and the frequency parameter of the lid oscillation, ω′ ≤ 10.0. Comprehensive details of the flow structure are analyzed. Attention is focused on the three-dimensionality of the flow field. Extensive numerical flow visualizations have been performed. These yield sequential plots of the main flows as well as the secondary flow patterns. It is found that the previous two-dimensional computational results are adequate in describing the main flow characteristics in the bulk of interior when ω′ is reasonably high. For the cases of high-Re flows, however, the three-dimensional motions exhibit additional complexities especially when ω′ is low. It is asserted that, thanks to the recent development of the supercomputers, calculation of three-dimensional, time-dependent flow problems appears to be feasible at least over limited ranges of Re.

scholarly journals Simulation and Analysis of a Turbulent Flow Around a Three-Dimensional Obstacle

2019 ◽  
Vol 13 (3) ◽  
pp. 173-180
Author(s):  
Lamia Benahmed ◽  
Khaled Aliane
Keyword(s):  
Shear Stress ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Turbulence Models ◽  
Governing Equations ◽  
Complex Behaviour ◽  
Ansys Cfx ◽  
Recirculation Zones ◽  
Volume Method ◽  
Calculation Code

Abstract The study of flow around obstacles is devised into three different positions: above the obstacle, upstream of the obstacle, and downstream of the latter. The behaviour of the fluid downstream of the obstacle is less known, and the physical and numerical modelling is being given the existence of recirculation zones with their complex behaviour. The purpose of the work presented below is to study the influence of the inclined form of the two upper peaks of a rectangular cube. A three-dimensional study was carried out using the ANSYS CFX calculation code. Turbulence models have been used to study the flow characteristics around the inclined obstacle. The time-averaged results of contours of velocity vectors <V>, cross-stream <v> and stream wise velocity <u> and streamlines were obtained by using K-ω shear -stress transport (SST), RANG K-ε and K-ε to model the turbulence, and the governing equations were solved using the finite volume method. The turbulence model K-ω SST has presented the best prediction of the flow characteristics for the obstacle among the investigated turbulence models in this work.

A Thermohydrodynamic Analysis of Foil Journal Bearings

2006 ◽  
Vol 128 (3) ◽  
pp. 534-541 ◽  
Author(s):  
Z-C. Peng ◽  
M. M. Khonsari
Keyword(s):  
Reasonable Agreement ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Temperature Characteristic ◽  
Journal Bearings ◽  
Bearing Surface ◽  
Wide Range ◽  
Parametric Studies ◽  
Load Conditions

A thermohydrodynamic model is developed for predicting the three-dimensional (3D) temperature field in an air-lubricated, compliant foil journal bearing. The model accounts for the compressibility and the viscosity-temperature characteristic of air and the compliance of the bearing surface. The results of numerical solutions are compared to published experimental measurements and reasonable agreement has been attained. Parametric studies covering a fairly wide range of operating speeds and load conditions were carried out to illustrate the usefulness of the model in terms of predicting the thermal performance of foil journal bearings.

On the Behavior of Misaligned Journal Bearings Based on Mass-Conservative Thermohydrodynamic Analysis

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
J. Y. Jang ◽  
M. M. Khonsari
Keyword(s):  
Flow Rate ◽  
Thermal Field ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Comprehensive Analysis ◽  
Leakage Flow ◽  
Performance Parameters ◽  
Film Rupture ◽  
Leakage Flow Rate

Misalignment affects nearly all the bearing performance parameters including the cavitation, thermal field, leakage flow-rate, and moments. The present paper provides a comprehensive analysis of misaligned journal bearings based on a three-dimensional mass-conservative thermohydrodynamic model that appropriately takes into account the film rupture and reformation. An extensive set of numerical solutions are presented to closely examine the effects of misalignment in journal bearings.

Inertia Effect on the Thermohydrodynamic Characteristics of Journal Bearings

2005 ◽  
Vol 219 (6) ◽  
pp. 459-467 ◽  
Author(s):  
Gandjalikhan S. A. Nassab
Keyword(s):  
Numerical Solutions ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Navier Stokes ◽  
Radial Clearance ◽  
Inertia Effect ◽  
Fluid Inertia ◽  
Lubricant Flow ◽  
Simplifying Assumptions

In this article, the effect of lubricant inertia on the thermohydrodynamic behaviour of journal bearings is studied. Many researchers have analysed the inertia effect on lubricant flow in bearings using different simplifying assumptions. The purpose of this study is to eliminate most of those assumptions, using computational fluid dynamics (CFD) techniques to solve the exact governing equations. The bearing has a finite length and operates under incompressible laminar flow and steady conditions. Numerical solutions of the full three-dimensional Navier-Stokes equations with and without inertia terms, coupled with the energy equation in the lubricant flow and the heat conduction equations in the bearing and the shaft are obtained. Cavitation effects are also considered using an appropriate three-dimensional cavitation model. In order to study the effect fluid inertia under several different conditions, solutions are obtained for different values of the eccentricity and radial clearance and also for different values of the rotational speed of the shaft. To validate the computational results, comparison with the experimental data of other investigators is made, and reasonable agreement is obtained.

Numerical and Experimental Investigation of Flow Through Vane Swirlers

2005 ◽  
Author(s):  
R. Thundil Karuppa Raj ◽  
V. Ganesan
Keyword(s):  
Loss Factor ◽  
Computational Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Stress Model ◽  
Governing Equations ◽  
Three Dimensional Flow ◽  
Turbulence Effects ◽  
Flow Through ◽  
Vane Angle

This paper is concerned with the computational and experimental study of steady flow through vane swirlers for various vane angles from 15° to 60° in steps of 15°. In the computational study the geometry and meshing is done using pre-processor GAMBIT. Three dimensional flow within the geometry and through the swirler has been simulated by solving the appropriate governing equations viz. conservation of mass and momentum using FLUENT code. Turbulence effects are taken care of by the Reynolds stress model for high swirls and standard k-ε model for low swirls. The effects of vane angle on flow characteristics have been studied. A parametric study is done for a 45° vane swirler to investigate the effect of number of vanes. Experimental results of axial velocity profiles downstream of the swirler are found to be in close agreement with the numerical results. The total pressure loss factor, maximum reverse velocity and maximum reverse mass flow for each swirler are determined

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