A Review of Journal Bearing Thermal Effects on Rotordynamic Response

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Dongil Shin ◽  
Jongin Yang ◽  
Xiaomeng Tong ◽  
Junho Suh ◽  
Alan Palazzolo
Keyword(s):  
Thermal Effects ◽  
High Performance ◽  
Thermal Instability ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Critical Role ◽  
Journal Bearings ◽  
Constant Viscosity ◽  
Bearing Design ◽  
Dynamics Models

Abstract Traditional analysis of journal bearings assumed a constant viscosity which simplified the solutions for static and dynamic characteristics and responses. Today's high-performance machinery requires more accurate models wherein temperature and viscosity distributions in the film must be calculated. Thermal effects in journal bearings have a strong influence on both static and dynamic properties, and consequently play a critical role in determining rotor-bearing system performance. This paper presents an extensive survey of the thermal modeling methods and effects in journal bearings. The subjects include various bearing types, and recent progress in thermal bearing design and thermal instability problems observed in fluid and gas film hydrodynamic bearings. The extent of the survey ranges from conventional Reynolds equation models to more advanced computational fluid dynamics models.

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.

Experimental Study of Thermal Effects in Tilting-Pad Journal Bearings at High Operating Speeds

1996 ◽  
Vol 118 (3) ◽  
pp. 532-538 ◽  
Author(s):  
C. Bouchoule ◽  
M. Fillon ◽  
D. Nicolas ◽  
F. Barresi
Keyword(s):  
Thermal Effects ◽  
Applied Load ◽  
Journal Bearings ◽  
Test Machine ◽  
Power Losses ◽  
Test Bed ◽  
Tilting Pad ◽  
Oil Flow ◽  
Bearing Design ◽  
Tilting Pad Journal Bearings

In this work, a test machine, experimental results and the comparison between theoretical TEHD results and experimental data are presented. The tested bearings are located in two speed increasing and reduction gearboxes (back-to-back test bed). The shaft is driven by a 1 MW motor. The bearing diameter and the bearing length are equal to 160 mm. The rotational speed varies from 2700 rpm (22 m/s) to 11,880 rpm (100 m/s). The applied load is up to 88,000 N. Temperatures in the bearing (film/pad interface, oil, pad and housing), power losses and oil flow are measured. The influence of the bearing design and of the pivot position on the pad is analyzed.

Dynamic Identification of 280mm Diameter Tilting Pad Journal Bearings: Test Results and Measurement Uncertainties Assessment of Different Designs

2020 ◽  
Author(s):  
Riccardo Ferraro ◽  
Alice Innocenti ◽  
Mirko Libraschi ◽  
Michele Barsanti ◽  
Enrico Ciulli ◽  
...  
Keyword(s):  
High Performance ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
Turbulent Regime ◽  
Dynamic Identification ◽  
Damping Characteristics ◽  
Flexible Rotors ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Abstract Tilting pad journal bearings (TPJBs) are crucial elements in turbomachinery applications providing stiffness and damping characteristics that determine rotor system dynamic behavior. Hence, a correct design and an accurate dynamic properties prediction is fundamental for the successful industrial operation of rotating machinery. Current design trends in turbomachinery aiming at higher efficiency and power through weight optimization and higher operating speeds determine the development of large flexible rotors that are particularly important from the rotordynamic standpoint. The dynamic feasibility of this type of machine relies on bearing stiffness and damping characteristics that must be predicted with a certain level of confidence in order to increase the accuracy of the expected rotordynamic behaviour and avoid unpredicted vibration issues when rotors are operated. Furthermore, large centrifugal compressors commonly used in Liquified Natural Gas (LNG) applications make the bearings operate at very high peripheral speed where the transition from laminar to turbulent regime occurs, increasing the necessity of predictions accuracy. In this paper a test campaign on different large TPJB solutions operating in turbulent lubrication regime has been performed on a dedicated test rig designed for investigations on large size high-performance oil bearings. In the present work both static performance and dynamic identification of the tested TPJB solutions are presented and compared to numerical model predictions. The results of an uncertainty quantification, performed to validate the experimental results, are also shown.

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.

Pseudospectral Orbit Simulation of Nonideal Gas-Lubricated Journal Bearings for Microfabricated Turbomachines

1999 ◽  
Vol 121 (3) ◽  
pp. 604-609 ◽  
Author(s):  
E. S. Piekos ◽  
K. S. Breuer
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Published Data ◽  
Simulation Tool ◽  
Orbit Method ◽  
Nonideal Gas ◽  
Stability Chart ◽  
Bearing Design

A journal bearing simulation tool developed to aid the design of the MIT microturbo-machine bearings is described. This tool uses an orbit method with a pseudospectral technique for treating the Reynolds equation. Comparison is made to various published data. Two types of stability chart are presented and their application to turbo-machine bearing design is discussed. Simulations of imbalance, noncircular geometry, and nonuniform pressures at the bearing ends are also demonstrated.

Modeling of Flexible Tilting Pad Journal Bearings With Radial Oil Injection

2008 ◽  
Author(s):  
Asger M. Haugaard ◽  
Ilmar F. Santos
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Journal Bearings ◽  
System Of Equations ◽  
Servo Valve ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
Oil Injection ◽  
Tilting Pad Journal Bearings

The static and dynamic properties of tilting-pad journal bearings with controllable radial oil injection are investigated. The tilting pads are modelled as flexible structures and their dynamics are described using a three dimensional finite element framework and linear elasticity. The oil film pressure and flow are considered to follow the modified Reynolds equation, which includes the contribution from controllable radial oil injection. The Reynolds equation is solved using a two dimensional finite element mesh. The rotor is considered to be rigid. The servo-valve flow is governed by a second order ordinary differential equation, where the right hand side is controlled by an electronic input signal. The constitutive flow pressure relationship of the injection nozzles is that of a fully developed laminar velocity profile and the servo-valve is introduced into the system of equations by a volume conservation consideration. The Reynolds equation is linearized with respect to displacements and velocities of the nodal degrees of freedom. When all nodal points satisfy the static equilibrium condition, the system of equations is dynamically perturbed and subsequently condensed to a 2 by 2 system, keeping only the lateral motion of the rotor. As expected, rotor stability is heavily influenced by the control parameters.

Efficiency Analysis of Rapid Turbocharger With Alternative Bearing Design

2005 ◽  
Vol 128 (1) ◽  
pp. 137-141 ◽  
Author(s):  
Abdelkrim Liazid ◽  
Lahouari Izidi ◽  
Mohamed Bencherif
Keyword(s):  
Diesel Engine ◽  
Reynolds Equation ◽  
Efficiency Analysis ◽  
Journal Bearings ◽  
Air Bearing ◽  
Global Evolution ◽  
Bearing Load ◽  
Innovative Idea ◽  
Bearing Design

This work presents the possibility to adapt self-acting air bearing to a rapid diesel engine turbocharger originally designed with oil journal bearings. The aim of this innovative idea is to estimate a global evolution of efficiency which is a parameter that strongly influences the inlet air mass of the diesel engine. This study deals with radial bearings and illustrates the advantages and the limits of the aerodynamic bearing application. First, the computing concerns the determination of the bearing load by resolving the Reynolds equation. So, the determination of the neat turbine power by a mathematical model using some experimental data is also made. Lastly, a comparison with the original hydrodynamic bearings is presented. Some discussions are also developed.

Static and Dynamic Characteristics for a Pressure-Dam Bearing

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Bader Al-Jughaiman ◽  
Dara Childs
Keyword(s):  
Frequency Ratio ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Added Mass ◽  
Equation Model ◽  
Journal Bearings ◽  
Infinite Length ◽  
Fluid Inertia ◽  
Test Conditions ◽  
Load Conditions

Measured rotordynamic force coefficients (stiffness, damping, and added mass) and static characteristics (eccentricity and attitude angle) of a pressure-dam bearing are presented and compared to predictions from a Reynolds-equation model, using an isothermal and isoviscous laminar analysis. The bearing’s groove dimensions are close to the optimum predictions of Nicholas and Allaire (1980, “Analysis of Step Journal Bearings-Infinite Length and Stability,” ASLE Trans., 22, pp. 197–207) and are consistent with current field applications. Test conditions include four shaft speeds (4000rpm, 6000rpm, 8000rpm, and 10000rpm) and bearing unit loads from 0kPato1034kPa(150psi). Laminar flow was produced for all test conditions. A finite-element algorithm was used to generate solutions to the Reynolds-equation model. Excellent agreement was found between predictions and measurements for the eccentricity ratio and attitude angles. Predictions of stiffness and damping coefficients are in reasonable agreement with measurements. However, experimental results show that the bearing has significant added mass of about 60kg at no-load conditions, versus zero mass for predictions from the Reynolds-equation model and 40kg using Reinhardt and Lund’s (1975, “The Influence of Fluid Inertia on the Dynamic Properties of Journal Bearings,” ASME J. Lubr. Technol., 97, pp. 159–167) extended Reynolds-equation model for a plain journal bearing. The added mass quickly drops to zero as the load increases. Measured results also show a whirl frequency ratio near 0.36 at no-load conditions; however, a zero whirl frequency ratio was obtained at all loaded conditions, indicating an inherently stable bearing from a rotordynamics viewpoint.

Elastohydrodynamics Applied to Active Tilting-Pad Journal Bearings

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Asger M. Haugaard ◽  
Ilmar F. Santos
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Dynamic Properties ◽  
Flexible Structures ◽  
Journal Bearings ◽  
System Of Equations ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
Oil Injection ◽  
Tilting Pad Journal Bearings

The static and dynamic properties of tilting-pad journal bearings with controllable radial oil injection are investigated theoretically. The tilting pads are modeled as flexible structures and their behavior is described using a three-dimensional finite element framework and linear elasticity. The oil film pressure and flow are considered to follow the modified Reynolds equation, which includes the contribution from controllable radial oil injection. The Reynolds equation is solved using a two-dimensional finite element mesh. The rotor is considered to be rigid in terms of shape and size, but lateral movement is permitted. The servovalve flow is governed by a second order ordinary differential equation, where the right hand side is controlled by an electronic input signal. The constitutive flow-pressure relationship of the injection orifices is that of a fully developed laminar velocity profile and the servovalve is introduced into the system of equations by a mass conservation consideration. The Reynolds equation is linearized with respect to displacements and velocities of the nodal degrees of freedom. When all nodal points satisfy static equilibrium, the system of equations is dynamically perturbed and subsequently condensed to a 2×2 system, keeping only the lateral motion of the rotor. As expected, bearing dynamic coefficients are heavily influenced by the control parameters and pad compliance.

On Journal Bearings of Finite Length With Variable Viscosity

1959 ◽  
Vol 26 (2) ◽  
pp. 179-183
Author(s):  
L. N. Tao
Keyword(s):  
Exact Solution ◽  
Analytical Solution ◽  
Finite Length ◽  
Reynolds Equation ◽  
Variable Viscosity ◽  
Load Capacity ◽  
Journal Bearings ◽  
Heun Functions ◽  
Load Vector ◽  
Constant Viscosity

Abstract An exact solution of the Reynolds equation for journal bearings of finite length with viscosity as a function of pressure is found. The analytical solution is expressed in terms of Heun functions. The load capacity and the attitude angle are derived. It is found that the load vector, in general, is not perpendicular to the line of journal and bearing centers as shown in the constant-viscosity case.

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