Reducing Friction in Tilting-Pad Bearings by the Use of Enclosed Recesses

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Niels Heinrichson ◽  
Ilmar Ferreira Santos
Keyword(s):  
Power Loss ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Accurate Analysis ◽  
Pivot Point ◽  
Analysis And Design ◽  
Sliding Direction ◽  
Tilting Angle ◽  
Tilting Pad ◽  
Tilting Pad Bearings

A three-dimensional thermoelastohydrodynamic model is applied to the analysis of tilting-pad bearings with spherical pivots and equipped with deep recesses in the high-pressure regions. A potential for a 10–20% reduction in the friction loss compared to conventional plain bearing pads is documented. Design suggestions minimizing the power loss are given for various length-to-width ratios. The tilting angle in the sliding direction is more sensitive to correct positioning of the pivot point than conventional bearing pads. Improving the performance by equipping a tilting-pad bearing with a deep recess therefore requires accurate analysis and design of the bearing. Similarly, a high sensitivity perpendicular to the sliding direction suggests that this method of reducing friction is more feasible when using line pivots or spring beds than when using spherical pivots for controlling the tilting angle.

On the Thermal Effects in the Design of Tilting-Pad Bearings Subjected to Inlet Pressure Build-Up

1991 ◽  
Vol 113 (3) ◽  
pp. 526-532 ◽  
Author(s):  
K. W. Kim ◽  
C. M. Rodkiewicz
Keyword(s):  
Thermal Effects ◽  
Center Of Pressure ◽  
Load Capacity ◽  
Inlet Pressure ◽  
Maximum Temperature ◽  
Pivot Point ◽  
Temperature Distributions ◽  
Tilting Pad ◽  
Tilting Pad Bearings ◽  
Force Coordinate

The presented analytical consideration of tilting-pad bearings incorporates simultaneously the changes in viscosity (due to viscous dissipation) and in the nonambient inlet pressure (due to momentum depletion within the fore-region). The solution provides the following quantities: film temperature distributions, pressure distribution, maximum temperature of the pad, load capacity, friction force, coordinate of the center of pressure, and coordinate of the pivot point. Comparison with the case when the inlet pressure is assumed to be ambient indicates the significance of the pressure build-up in the fore-region.

Reduction of Vibration and Power Loss in Industrial Turbochargers With Improved Tilting Pad Bearing Design

2015 ◽  
Author(s):  
Jianming Cao ◽  
Timothy Dimond ◽  
Paul Allaire
Keyword(s):  
Rotational Speed ◽  
Power Loss ◽  
Internal Combustion Engines ◽  
Low Cost ◽  
Stability Margin ◽  
Reciprocating Compressor ◽  
Automotive Applications ◽  
Run Off ◽  
Tilting Pad ◽  
Tilting Pad Bearings

Turbochargers are commonly used in reciprocating compressors and internal combustion engines to improve overall efficiency, thereby reducing fuel requirements. In reciprocating compressor applications, turbochargers typically operate in the range of 15,000 rpm to 30,000 rpm. These turbomachines operate at higher rotational speed in automotive applications, often exceeding 100,000 rpm. These high speeds result in bearings that are often highly non-linear, with large limit cycle shaft orbits and high subsynchronous vibration levels. These large orbits also result in much higher power losses than would be observed for the same bearing with low vibration levels. These devices are often used in automotive applications, where there are significant cost pressures, ruling out more expensive bearing options such as tilting pad bearings. There is a need for bearing designs that are effective at stabilizing turbochargers and are also low cost. In this paper, a theoretical turbocharger for a reciprocating compressor application is considered. The initial design incorporated plain axial groove bearings. Several replacement bearing options were considered, including pressure dam bearings and tilting pad bearings to improve rotor stability. The pressure dam bearing is used to impose a load on the shaft, making it run off center. This feature reduces subsynchronous whirl instability and also reduces power loss. The tilting pad bearing eliminates self-excited forces from the bearings but has increased power loss when compared to fixed-pad bearings. Starved lubrication of the tilting pad bearing reduced the power loss but also reduced the stability margin. The application considered for this paper is a larger turbocharger with a rotational speed of 25,000 rpm, and is unstable with conventional bearings.

Research on Thermal Characteristics of Spindle System With Tilting Pad Bearing

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Shuyun Jiang ◽  
Deyang Shen
Keyword(s):  
Power Loss ◽  
Thermal Model ◽  
Thermal Characteristics ◽  
The Finite Element Method ◽  
Spindle System ◽  
Friction Power ◽  
Heat Transfer Theory ◽  
Lubricant Flow ◽  
Tilting Pad ◽  
Tilting Pad Bearings

Spindles with tilting pad bearings have been widely applied in machine tools due to their high running precision. However, friction power loss will increase dramatically when the bearing runs at a higher speed. So far, little research on the thermal modeling of spindle systems with tilting pad bearings can be found in literature. In this paper, based on the Newtonian law of viscosity, formula that describes the friction power loss of the tilting pad bearing has been derived. The thermodynamic equilibrium equation for the spindle lubrication system has been established. Thermal boundary condition of the spindle system has been obtained using the heat transfer theory. Thermal model of the spindle system with tilting pad bearing has been built with the finite element method in order to calculate its temperature and thermal displacement distribution. Effects of the eccentricity ratio and the lubricant flow rate on thermodynamic behavior of the spindle system have been studied systematically. Finally, experiments have been conducted to verify the proposed thermal model for the spindle system with tilting pad bearing.

Influence of Elastic Deformations of Turbo-Generator Tilting Pad Bearings on the Static Behavior and on the Dynamic Coefficients in Different Designs

1989 ◽  
Vol 111 (2) ◽  
pp. 364-371 ◽  
Author(s):  
D. Brugier ◽  
M. T. Pascal
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Operating Conditions ◽  
Three Dimensional Model ◽  
Static Loads ◽  
Turbo Generator ◽  
Tilting Pad ◽  
Dimensional Finite Element ◽  
Tilting Pad Bearings ◽  
Three Dimensional Finite Element

The load on the larger tilting pad bearing can be as high as 106 N. With such high static loads, pad and pivot distortions and thermal effects in the lubricant cannot be neglected. This paper analyzes the influence of the deformation of the pads and pivots on the static and dynamic behavior of typical turbo-generator tilting pad bearings used in actual operating conditions. Thermal and pressure distortions are compared. The hydrodynamic pressures and lubricant temperatures are computed with a three-dimensional model. Thermal and elastic pad and pivot distortions are obtained with a three-dimensional finite element model.

Lund’s Pad Assembly Method for Tilting Pad Journal Bearings

2001 ◽  
Author(s):  
John C. Nicholas
Keyword(s):  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Analysis And Design ◽  
Simple Addition ◽  
Assembly Method ◽  
Elasticity Equations ◽  
Tilting Pad ◽  
Tilting Pad Bearings ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

Abstract This paper summarizes the development during the last 50 years of tilting pad journal bearing analysis and design. The major impetus of this development was a landmark paper published by Jorgen Lund in 1964, “Spring and Damping Coefficients for the Tilting-Pad Journal Bearing.” His paper contained the first widely published dynamic coefficients for tilting pad bearings along with his pad assembly method equations. In the 37 years since Lund’s publication, many other authors have written tilting pad journal bearing codes, the first of which were based on Lund’s assembly method. These assembly method codes were utilized for many years to analyze and design tilting pad bearings for improved rotordynamic performance. During this time, some key design tools were developed utilizing Lund’s method. Other authors have written newer codes which solve the energy and elasticity equations iteratively with the pressure equation, including pad degrees of freedom. With the simple addition of a turbulence correction and heat balance, many designers continue to utilize Lund’s method, shunning the more modern codes.

Constrained Design Optimization of Rotor-Tilting Pad Bearing Systems

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Costin D. Untaroiu ◽  
Alexandrina Untaroiu
Keyword(s):  
Design Optimization ◽  
Power Loss ◽  
Optimization Design ◽  
Optimization Approach ◽  
Design Variables ◽  
Tilting Pad ◽  
Rotor Bearing ◽  
Automatic Optimization ◽  
Tilting Pad Bearings ◽  
Bearing System

Design of a rotor-bearing system is a challenging task due to various conflicting design requirements, which should be fulfilled. This study considers an automatic optimization approach for the design of a rotor supported on tilting-pad bearings. A numerical example of a rotor-bearing system is employed to demonstrate the merits of the proposed design approach. The finite element method is used to model the rotor-bearing system, and the dynamic speed-dependent coefficients of the bearing are calculated using a bulk flow code. A number of geometrical characteristics of the rotor simultaneously with the parameters defining the configuration of tilting pad bearings are considered as design variables into the automatic optimization process. The power loss in bearings, stability criteria, and unbalance responses are defined as a set of objective functions and constraints. The complex design optimization problem is solved using heuristic optimization algorithms, such as genetic, and particle-swarm optimization. Whereas both algorithms found better design solutions than the initial design, the genetic algorithms exhibited the fastest convergence. A statistical approach was used to identify the influence of the design variables on the objective function and constraint measures. The bearing clearances, preloads and lengths showed to have the highest influence on the power loss in the chosen design space. The high performance of the best solution obtained in the optimization design suggests that the proposed approach has good potential for improving design of rotor-bearing systems encountered in industrial applications.

Lund’s Tilting Pad Journal Bearing Pad Assembly Method

2003 ◽  
Vol 125 (4) ◽  
pp. 448-454 ◽  
Author(s):  
John C. Nicholas
Keyword(s):  
Degrees Of Freedom ◽  
Journal Bearing ◽  
Design Tools ◽  
Analysis And Design ◽  
Simple Addition ◽  
Assembly Method ◽  
Elasticity Equations ◽  
Tilting Pad ◽  
Tilting Pad Bearings ◽  
Tilting Pad Journal Bearing

This paper summarizes the development during the last 50 years of tilting pad journal bearing analysis and design. The major impetus of this development was a landmark paper published by Jørgen Lund in 1964, “Spring and Damping Coefficients for the Tilting-Pad Journal Bearing.” His paper contained the first widely published dynamic coefficients for tilting pad bearings along with his pad assembly method equations. In the 38 years since Lund’s publication, many other authors have written tilting pad journal bearing codes, the first of which were based on Lund’s assembly method. These assembly method codes were utilized for many years to analyze and design tilting pad bearings for improved rotordynamic performance. During this time, some key design tools were developed utilizing Lund’s method. Other authors have written newer codes which solve the energy and elasticity equations iteratively with the pressure equation, including pad degrees of freedom. With the simple addition of a turbulence correction and heat balance, many designers continue to utilize Lund’s method, shunning the more modern codes.

An Efficient Quasi-Three-Dimensional Model of Tilting Pad Journal Bearing for Turbomachinery Applications

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Andrea Rindi ◽  
Stefano Rossin ◽  
R. Conti ◽  
A. Frilli ◽  
E. Galardi ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Cost ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Journal Bearings ◽  
Three Dimensional Model ◽  
Accurate Analysis ◽  
Technical Data ◽  
Plant Behavior ◽  
Tilting Pad

The constant increase of turbomachinery rotational speed has brought the design and the use of journal bearings to their very limits: tilting pad journal bearings (TPJBs) have been introduced for high-speed/high-load applications due to their intrinsic stability properties and can be used both in transient and steady-state operations obtaining superior performances. An accurate analysis of the TPJBs behavior is essential for a successful design and operation of the system; however, it is necessary to reach a compromise between the accuracy of the results provided by the TPJB model and its computational cost. This research paper exposes the development of an innovative and efficient quasi-3D TPJB modeling approach that allows the simultaneous analysis of the system rotordynamics and the supply plant behavior; the majority of existing models describe these aspects separately but their complex interaction must be taken into account to obtain a more accurate characterization of the system. Furthermore, the proposed model is characterized by a high numerical efficiency and modularity, allowing for complex transient simulations of the complete plant and for the representation of different kind of bearings. The TPJB model has been developed and experimentally validated in collaboration with an industrial partner which provided the technical data of the system and the results of experimental tests.

Analysis and design of suitable model structures for activated sludge tanks with circulating flow

1999 ◽  
Vol 39 (4) ◽  
pp. 55-60 ◽  
Author(s):  
J. Alex ◽  
R. Tschepetzki ◽  
U. Jumar ◽  
F. Obenaus ◽  
K.-H. Rosenwinkel
Keyword(s):  
Activated Sludge ◽  
Large Scale ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
High Sensitivity ◽  
Suitable Model ◽  
Model Structure ◽  
Analysis And Design ◽  
Hydraulic Behaviour ◽  
Model Structures

Activated sludge models are widely used for planning and optimisation of wastewater treatment plants and on line applications are under development to support the operation of complex treatment plants. A proper model is crucial for all of these applications. The task of parameter calibration is focused in several papers and applications. An essential precondition for this task is an appropriately defined model structure, which is often given much less attention. Different model structures for a large scale treatment plant with circulation flow are discussed in this paper. A more systematic method to derive a suitable model structure is applied to this case. Results of a numerical hydraulic model are used for this purpose. The importance of these efforts are proven by a high sensitivity of the simulation results with respect to the selection of the model structure and the hydraulic conditions. Finally it is shown, that model calibration was possible only by adjusting to the hydraulic behaviour and without any changes of biological parameters.

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