Analysis of Heavily Loaded Tilted Pads Thrust Bearings With Large Dimensions Under TEHD Conditions

1988 ◽  
Vol 110 (3) ◽  
pp. 467-476 ◽  
Author(s):  
L. A. Abdel-Latif
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Iterative Scheme ◽  
Equation System ◽  
Successive Approximation Method ◽  
Heavy Load ◽  
Thrust Bearings ◽  
Characteristic Values ◽  
Heavy Loads ◽  
Bearing Characteristic

Huge thrust bearings with centrally pivoted and tilted pads operating under heavy loads are analzyed using the (thermoelastohydrodynamic) TEHD-theory. The Reynolds equation, the energy equation of the oil film, and the heat conduction equation of the bearing, all are coupled with the deflection equation and solved simultaneously in order to determine the bearing characteristic values. The first three equations are transformed by means of finite difference method and the last equation is solved using the method of Ritz-Galerkin. Based on successive approximation method a new iterative scheme is presented to apply the heavy load incrementally which provides a successful convergence of the equation system. In order to find the equilibrium state of the pad, another iterative scheme based on a controlled change of the pad tilts is applied. The tilts are changed as a function of the offset of the hydrodynamic resultant force from the pivot location. It is proved that the new scheme is quite efficient in successful convergence of the equation system and in saving CPU time.

scholarly journals Run-Up Simulation of a Semi-Floating Ring Supported Turbocharger Rotor Considering Thrust Bearing and Mass-Conserving Cavitation

Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 44
Author(s):  
Christian Ziese ◽  
Cornelius Irmscher ◽  
Steffen Nitzschke ◽  
Christian Daniel ◽  
Elmar Woschke
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Three Dimensional ◽  
Reliable Prediction ◽  
Two Phase ◽  
Hydrodynamic Bearings ◽  
Thrust Bearings ◽  
Run Up ◽  
The Impact

The vibration behaviour of turbocharger rotors is influenced by the acting loads as well as by the type and arrangement of the hydrodynamic bearings and their operating condition. Due to the highly non-linear bearing behaviour, lubricant film-induced excitations can occur, which lead to sub-synchronous rotor vibrations. A significant impact on the oscillation behaviour is attributed to the pressure distribution in the hydrodynamic bearings, which is influenced by the thermo-hydrodynamic conditions and the occurrence of outgassing processes. This contribution investigates the vibration behaviour of a floating ring supported turbocharger rotor. For detailed modelling of the bearings, the Reynolds equation with mass-conserving cavitation, the three-dimensional energy equation and the heat conduction equation are solved. To examine the impact of outgassing processes and thrust bearing on the occurrence of sub-synchronous rotor vibrations separately, a variation of the bearing model is made. This includes run-up simulations considering or neglecting thrust bearings and two-phase flow in the lubrication gap. It is shown that, for a reliable prediction of sub-synchronous vibrations, both the modelling of outgassing processes in hydrodynamic bearings and the consideration of thrust bearing are necessary.

Thermohydrodynamic Performance of Thrust Bearings With Circular Tilted Pads Under the Presence of Air Gas Bubbles and Centrifugal Forces

1989 ◽  
Vol 111 (3) ◽  
pp. 510-517 ◽  
Author(s):  
L. A. Abdel-Latif ◽  
E. M. Bakr ◽  
M. I. Ghobrial
Keyword(s):  
Gas Bubbles ◽  
Lubricating Oil ◽  
Compressible Medium ◽  
Centrifugal Forces ◽  
Governing Equations ◽  
Thrust Bearings ◽  
Characteristic Values ◽  
The Finite Difference Method ◽  
Temperature And Pressure ◽  
Bearing Characteristic

This paper deals with the analysis of thrust bearings with tilted circular pads running under thermohydrodynamic conditions. During operation, a considerable quantity of air/gas bubbles is dispersed inside the lubricating oil and build a compressible medium. The important lubricant properties, namely viscosity and density are altered substantially due to bubble presence as well as temperature rise. The influence of the centrifugal forces become significant as the speed and load become higher. Such type of bearings has been herein investigated taking into account both influencing phenomena. The geometric and loading parameters are varied to show the combined effect on the bearing characteristic values. The governing equations of the THD theory are solved numerically using the finite difference method. The surface tension of bubbles and the change of bubble content with temperature and pressure are included in the governing equations as are the centrifugal forces.

An Analysis of Grease and Oil Lubricated Spiral Grooved Bearings

1974 ◽  
Vol 96 (2) ◽  
pp. 275-283
Author(s):  
D. M. Dewar
Keyword(s):  
Reynolds Equation ◽  
Energy Equation ◽  
Three Dimensional ◽  
Thermal Conditions ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Through Flow ◽  
Load Carrying ◽  
Running Torque ◽  
Spiral Groove Bearing

Mathematical models for grease and oils are put forward and used to solve a two-dimensional Reynolds’ equation with a quasi three-dimensional energy equation for any geometry of spiral groove bearing. Using numerical methods, results are presented for the temperature distributions in through-flow and block-centered thrust bearings; conical bearings and herringbone grooved journal bearings can also be dealt with. The overall bearing parameters, namely, load-carrying capacity, stiffness, and running torque at various eccentricity ratios are shown along with their dependence upon the prevailing thermal conditions.

Novel Approach Towards Thrust Bearing Pad Cooling

2014 ◽  
Author(s):  
F. A. Najar ◽  
G. A. Harmain
Keyword(s):  
Hot Spots ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Axial Loads ◽  
Cooling Systems ◽  
High Pressure And Temperature ◽  
Oil Film ◽  
Thrust Bearings ◽  
Novel Approach ◽  
Fourier Heat Conduction

The present paper analyzes the thermal effect on a sector shaped pad extensively used in thrust bearings which supports the heavy axial loads. Large hydro-generator thrust bearings are susceptible to too much thermo-elastic deformation when oil film thickness is subjected to high pressure and temperature which can even lead to the bearing failure. So as a remedy, this study is an effort towards reducing the oil film temperature by incorporating a suitable cooling treatment. The cooling circuit, in this study, essentially follows a path of hot spots observed by solving Reynolds equation, energy equation and generalized Fourier heat conduction equation. The numerical scheme followed during investigation is finite difference method (FDM). The water circuit developed is just beneath the Babbitt lining of the pads. It has been observed that overall temperature has reduced significantly as compared to traditional cooling systems.

An Inverse Solution to the Point Contact EHL Problem Under Heavy Loads

1987 ◽  
Vol 109 (3) ◽  
pp. 432-436 ◽  
Author(s):  
K. P. Hou ◽  
D. Zhu ◽  
S. Z. Wen
Keyword(s):  
Film Thickness ◽  
Numerical Scheme ◽  
Reynolds Equation ◽  
Point Contact ◽  
Inverse Solution ◽  
Computational Results ◽  
Heavy Load ◽  
Operating Region ◽  
Heavy Loads ◽  
The Stability

A set of computational results of the point contact EHL problem under heavily loaded condition is presented in this paper, and the numerical scheme for the inverse solution of the Reynolds Equation is developed. By using a deformation matrix to calculate the local elastic deformation and its inverse matrix to modify the pressure distribution, both the convergence and the stability of the numerical method are satisfactory. The examples of calculation adopted have been extended from Hamrock and Dowson’s cases into the operating region of heavy load. The results obtained have shown the effects of speed, load, and choice of materials on the film thickness, and have proved Hamrock and Dowson’s formulae for estimating film thicknesses to be accurate under heavily loaded condition.

Hydrodynamic Thrust Bearings: Theory and Experiment

1991 ◽  
Vol 113 (3) ◽  
pp. 633-638 ◽  
Author(s):  
A. K. Tieu
Keyword(s):  
Thermal Effects ◽  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Experimental Studies ◽  
Test Rig ◽  
Oil Viscosity ◽  
Thrust Bearings ◽  
Generalized Reynolds Equation

In this paper results from experimental studies and computer simulation of hydro-dynamic tilting thrust bearings are presented. The bearing performance in terms of outlet film thickness, friction coefficient, and bearing temperature was measured in a high speed thrust bearing test rig. The numerical simulation involves the solution of the generalized Reynolds equation and the energy equation, which considers thermal effects on the oil viscosity and the squeezing of the oil film.

Influence of slip-flow phenomenon on thermohydrodynamic behaviour of gas foil thrust bearings

2021 ◽  
pp. 135065012110029
Author(s):  
Jitesh Kumar ◽  
Debanshu S Khamari ◽  
Suraj K Behera ◽  
Ranjit K Sahoo
Keyword(s):  
Numerical Model ◽  
High Speed ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Slip Flow ◽  
Relaxation Method ◽  
Temperature Dependent Viscosity ◽  
High Rotational Speed ◽  
Thrust Bearings ◽  
Foil Bearings

Gas foil bearings are often used in high-speed turbomachinery such as turboexpanders and turbochargers due to their merits over simple gas-lubricated bearings. The merits of gas foil bearings include their ability to tailor dynamic parameters such as stiffness and damping. Gas foil bearings usually have low clearance and operate at a high rotational speed, which eventually leads to velocity slip at the solid–fluid interface. This article investigates the effect of slip flow on various parameters of gas foil thrust bearings. A numerical model is formulated to predict pressure, film thickness and temperature distribution of helium lubricated gas foil thrust bearing at high rotating speed. The Reynolds equation is modified by assuming first-order slip coupled with the structural (compliant) and energy equation. The temperature-dependent viscosity and density of the fluid are also considered in the Reynolds equation to predict the thermohydrodynamic behaviour of gas foil thrust bearings. The numerical model thus developed uses a finite-difference method and the Newton–Raphson method to solve the Reynolds equation,whereas the successive over-relaxation method is used to solve the energy equation. Various performance parameters are compared for slip and no-slip conditions for gas foil thrust bearings. The results show a considerable difference between the two phenomena. Also, the conventional Reynolds equation tends to overestimate the load-carrying capacity.

A Thermal Elastohydrodynamic Lubrication Model for Crowned Rollers and Its Application on Apex Seal–Housing Interfaces

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Zhong Liu ◽  
David Pickens III ◽  
Tao He ◽  
Xin Zhang ◽  
Yuchuan Liu ◽  
...  
Keyword(s):  
Temperature Rise ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Frictional Heating ◽  
Elastohydrodynamic Lubrication ◽  
Design Equation ◽  
Rotary Engine ◽  
Influence Coefficients ◽  
Heavy Loads ◽  
Thermal Ehl

This paper presents a thermal elastohydrodynamic lubrication (EHL) model for analyzing crowned roller lubrication performances under the influence of frictional heating. In this thermal EHL model, the Reynolds equation is solved to obtain the film thickness and pressure results while the energy equation and temperature integration equation are evaluated for the temperature rise in the lubricant and at the surfaces. The discrete convolution fast Fourier transform (DC-FFT) method is utilized to calculate the influence coefficients for both the elastic deformation and the temperature integration equations. The influences of the slide-to-roll ratio (SRR), load, crowning radius, and roller length on the roller lubrication and temperature rise are investigated. The results indicate that the thermal effect becomes significant for the cases with high SRRs or heavy loads. The proposed thermal EHL model is used to study the thermal-tribology behavior of an apex seal–housing interface in a rotary engine, and to assist the design of the apex seal crown geometry. A simplified crown design equation is obtained from the analysis results, validated through comparison with the optimal results calculated using the current crowned-roller thermo-EHL (TEHL) model.

On the Influence of Thrust Bearings on the Nonlinear Rotor Vibrations of Turbochargers

2016 ◽  
Author(s):  
Ioannis Chatzisavvas ◽  
Aydin Boyaci ◽  
Andreas Lehn ◽  
Marcel Mahner ◽  
Bernhard Schweizer ◽  
...  
Keyword(s):  
Hydrodynamic Model ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Oil Viscosity ◽  
Oil Film ◽  
Thrust Bearings ◽  
Run Up ◽  
Generalized Reynolds Equation

This work investigates the influence of hydrodynamic thrust bearings on the lateral rotor oscillations. Four thrust bearing models are compared in terms of their predictions of the oil-film pressure (Reynolds equation), the oil-film temperature (energy equation) and the load capacity. A detailed thrust bearing model using the generalized Reynolds equation and the 3D energy equation, a model using the standard Reynolds equation with a 2D energy equation, a model where the standard Reynolds equation and the 2D energy equation are decoupled and finally an isothermal thrust bearing model are presented. It is shown that in lower rotational speeds, the four models produce almost the same results. However, as the rotational speed is increased, the necessity for a thermo-hydrodynamic model is demonstrated. Run-up simulations of a turbocharger rotor/bearing system are performed, using an isothermal thrust bearing model with different inlet oil-temperatures. The influence of the oil-temperature of the thrust bearing on the subsynchronous rotor oscillations is investigated. Finally, a thermo-hydrodynamic model is compared with an isothermal in run-up simulations, where the influence of the variable oil-viscosity is discussed.

An Assessment of the Value of Theory in Predicting Gas-Bearing Performance

1961 ◽  
Vol 83 (2) ◽  
pp. 195-200 ◽  
Author(s):  
S. Cooper
Keyword(s):  
Steady State ◽  
Slip Velocity ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Experimental Methods ◽  
Experimental Results ◽  
Theoretical Investigations ◽  
Gas Bearing ◽  
Theoretical Results

The object of the paper is to indicate the value of theoretical investigations of hydrodynamic finite bearings under steady-state conditions. Methods of solution of Reynolds equation by both desk and digital computing, and methods of stabilizing the processes of solution, are described. The nondimensional data available from the solutions are stated. The outcome of an attempted solution of the energy equation is discussed. A comparison between some theoretical and experimental results is shown. Experimental methods employed and some difficulties encountered are discussed. Some theoretical results are given to indicate the effects of the inclusion of slip velocity, stabilizing slots, and a simple case of whirl.

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