A Thermohydrodynamic Analysis of Journal Bearings

1979 ◽  
Vol 101 (1) ◽  
pp. 21-27 ◽  
Author(s):  
T. Suganami ◽  
A. Z. Szeri
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Heat Conduction ◽  
Finite Element Methods ◽  
Energy Equation ◽  
Journal Bearings ◽  
Eddy Diffusivities ◽  
Sliding Motion ◽  
Theoretical Predictions ◽  
Film Lubrication

An attempt is made to formulate a thermohydrodynamic model of film lubrication, that is valid in both laminar and superlaminar flow regimes. The model represents turbulence by eddy diffusivities and, in the manner of Ng and Pan, considers the flow to be a small perturbation of turbulent Couette flow. The energy equation retains heat conduction in the direction of sliding motion, thus making the analysis applicable even at large eccentricities when backflow of the lubricant occurs. The equations are solved by finite element methods. Theoretical predictions are compared with two sets of experimental data, one set hitherto unpublished.

scholarly journals Development of a new test rig for the analysis of hydrodynamic bearings for rotors of microGT

2019 ◽  
Vol 113 ◽  
pp. 03002
Author(s):  
Carlo Alberto Niccolini Marmont Du Haut Champ ◽  
Fabrizio Stefani ◽  
Paolo Silvestri
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Gas Turbines ◽  
Dynamic Interaction ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Test Rig ◽  
Small Clearance ◽  
Stiffness And Damping ◽  
Good Agreement

The aim of the present work is to design a test rig suited to investigate the dynamic interaction between rotor and hydrodynamic journal bearings in micro gas turbines (microGT), i.e. with reference to small bearings (diameter in the order of ten millimeters). Particularly, the device is capable of measuring the journal location. Therefore, the journal motion due to rotor vibrations can be displayed, in order to assess performance as well as stiffness and damping of the bearings. The new test rig is based on Bently Nevada Rotor Kit (RK), but substantial modifications are carried out. Indeed, the relative radial clearance of the original RK bearings is about 2/100, while it is in the order of 1/1000 in industrial bearings. Therefore, the same RK bearings are employed in the new test rig, but a new shaft has been designed in order to reduce the original clearance. The new shaft enables us to study the bearing behaviour for different clearances, as it is equipped with interchangeable journals. The experimental data yielded by the new test rig are compared with numerical results. These are obtained by means of a suitable finite element (FEM) code developed by our research group. It allows the Thermo Elasto-HydroDynamic (TEHD) analysis of the bearing in static and dynamic conditions. In the present paper, bearing static performances are analysed in order to assess the reliability of the journal location predictions by comparing numerical and experimental results. Such comparisons are presented for both large and small clearance bearings of original and modified RK, respectively. Good agreement is found only for the modified RK equipped with small clearance bearings (relative radial clearance equal to 8/1000). Nevertheless, rotor alignment is quite difficult with small clearance bearings and a completely new test rig is designed for future experiments.

scholarly journals Theoretical and Experimental Investigations on Transient Run-Up Procedures of Journal Bearings Including Mixed Friction Conditions

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 105 ◽  
Author(s):  
Maximilian Prölß ◽  
Hubert Schwarze ◽  
Thomas Hagemann ◽  
Philipp Zemella ◽  
Philipp Winking
Keyword(s):  
Experimental Data ◽  
Energy Equation ◽  
Hydrodynamic Lubrication ◽  
Frictional Coefficient ◽  
Journal Bearings ◽  
Numerical Code ◽  
Experimental Investigations ◽  
Lubrication Regime ◽  
Mixed Friction ◽  
Run Up

This paper focuses on the operating behavior of journal bearings for industrial machinery application during run-ups. For this purpose, a numerical simulation code that is based on a two-dimensional extended and generalized Reynolds equation and a full three-dimensional energy equation, was advanced by a theoretical model considering the effects of mixed friction and warming of journal components during start-up. The mixed friction routine contained the elastic half-spaces model proposed by Boussinesq, which considers the influence of rough surfaces by implementing flow factors and calculates additional stiffness and dissipation in areas with solid interactions. Furthermore, a transient term was added in the energy equation to consider the thermal inertia of journal, and bearing to ensure a realistic heating during run-ups. Results of the prediction were compared to experimental data taken from a special test rig built up for validation procedures. Besides the conventional sensors for temperature, oil flow, and relative motion between shaft and stator, a contact voltage measurement was installed to determine the intensity of mixed friction. The evaluation of experimental data by Stribeck curves, based on a shaft torsion measurement, indicated a significant influence of run-up time on frictional moment. The friction coefficient of the rotor bearing system was strongly influenced by the run-up time. A short run-up time reduced the frictional coefficient in the mixed lubrication regime while the opposite behavior was observed in the hydrodynamic lubrication regime. The numerical code predicted these tendencies in good agreement with experimental data, however, only if the transient energy model was applied.

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

A Transient Thermoelastohydrodynamic Study of Steadily Loaded Plain Journal Bearings Using Finite Element Method Analysis

1999 ◽  
Vol 122 (1) ◽  
pp. 219-226 ◽  
Author(s):  
Bogdan-Radu Kucinschi ◽  
Michel Fillon ◽  
Jean Fre^ne ◽  
Mircea D. Pascovici
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Journal Bearing ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
Thermal Boundary Conditions ◽  
Theoretical Predictions ◽  
Start Ups ◽  
Method Analysis ◽  
Element Method

The present paper proposes an advanced bidimensional model necessary to calculate the temperature field in a journal bearing submitted to both rapid and slow start-ups. The model takes into account realistic thermal boundary conditions at fluid film-solid interfaces. The thermoelastic deformations of both the journal and of the bush are also considered and a special attention is paid to the ruptured zone of the film. The Finite Element Method (with upwind techniques whenever necessary) is employed to solve the equations implied by the model. Finally, the theoretical predictions were validated by comparison with experimental data. [S0742-4787(00)02701-6]

Application of a Finite Element Quasi-3D Solution of the Energy Equation to the TEHD Analysis of Dynamically Loaded Journal Bearings

2006 ◽  
Author(s):  
Fabrizio A. Stefani
Keyword(s):  
Finite Element ◽  
Energy Equation ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Lubricant Film ◽  
New Method ◽  
Hydrodynamic Problem ◽  
Mechanical Deformations ◽  
Dynamically Loaded ◽  
Oil Thickness

Taking advantage of the quasi-three-dimensional (quasi-3D) solution of the energy equation in the lubricant film presented in a previous work, a new method for analyzing the lubrication of dynamically loaded bearings is proposed. Cavitation is taken into account with a mass-conserving formulation of the hydrodynamic problem, where viscosity variations through the oil thickness are considered. The heat exchanged by the lubricant film with the bearing and the shaft is computed. Hence the thermo-elastic expansion of both the journal and the sleeve can be considered, together with the mechanical deformations of the bearing.

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