Design Charts for Optimum Bearing Configurations: 2—The Pivoted-Pad Thrust Bearing

1970 ◽  
Vol 92 (4) ◽  
pp. 572-577 ◽  
Author(s):  
R. Bosma ◽  
H. Moes
Keyword(s):  
Thrust Bearing ◽  
Journal Bearings ◽  
Thrust Bearings ◽  
Design Chart ◽  
Design Charts ◽  
Dimensionless Groups ◽  
Minimum Film Thickness ◽  
New Type ◽  
Complete Set ◽  
Film Stiffness

As a followup to an earlier paper in which a new type of design chart for full journal bearings was given a complete set of design charts for pivoted-pad thrust bearings (Michell bearings) shall now be presented. The dimensionless groups of parameters representing minimum film thickness and bearing traction for one single pad, respectively, have been plotted in a new design chart. Some illustrative examples demonstrating how to use the chart for optimization of pivoted-pad thrust bearings have been included. Some attention has also been paid to the stiffness of the film of lubricant. A design chart for film stiffness has been added to this purpose.

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Modeling and Experimental Investigation of Micro-hydrostatic Gas Thrust Bearings for Micro-turbomachines

2005 ◽  
Vol 128 (4) ◽  
pp. 597-605 ◽  
Author(s):  
C. J. Teo ◽  
Z. S. Spakovszky
Keyword(s):  
High Speed ◽  
Scaling Laws ◽  
Thrust Bearing ◽  
Journal Bearings ◽  
Axial Stiffness ◽  
Stable Operation ◽  
Successful Operation ◽  
Element Analysis ◽  
Essential Information ◽  
Thrust Bearings

One major challenge for the successful operation of high-power-density micro-devices lies in the stable operation of the bearings supporting the high-speed rotating turbomachinery. Previous modeling efforts by Piekos (2000, “Numerical Simulation of Gas-Lubricated Journal Bearings for Microfabricated Machines,” Ph.D. thesis, Department of Aeronautics and Astronautics, MIT), Liu et al. (2005, “Hydrostatic Gas Journal Bearings for Micro-Turbo Machinery,” ASME J. Vib. Acoust., 127, pp. 157–164), and Spakovszky and Liu (2005, “Scaling Laws for Ultra-Short Hydrostatic Gas Journal Bearings,” ASME J. Vib. Acoust. 127, pp. 254–261) have focused on the operation and stability of journal bearings. Thrust bearings play a vital role in providing axial support and stiffness, and there is a need to improve the understanding of their dynamic behavior. In this work, a rigorous theory is presented to analyze the effects of compressibility in micro-flows (characterized by low Reynolds numbers and high Mach numbers) through hydrostatic thrust bearings for application to micro-turbomachines. The analytical model, which combines a one-dimensional compressible flow model with finite-element analysis, serves as a useful tool for establishing operating protocols and assessing the stability characteristics of hydrostatic thrust bearings. The model is capable of predicting key steady-state performance indicators, such as bearing mass flow, axial stiffness, and natural frequency as a function of the hydrostatic supply pressure and thrust-bearing geometry. The model has been applied to investigate the static stability of hydrostatic thrust bearings in micro-turbine generators, where the electrostatic attraction between the stator and rotor gives rise to a negative axial stiffness contribution and may lead to device failure. Thrust-bearing operating protocols have been established for a micro-turbopump, where the bearings also serve as an annular seal preventing the leakage of pressurized liquid from the pump to the gaseous flow in the turbine. The dual role of the annular pad poses challenges in the operation of both the device and the thrust bearing. The operating protocols provide essential information on the required thrust-bearing supply pressures and axial gaps required to prevent the leakage of water into the thrust bearings. Good agreement is observed between the model predictions and experimental results. A dynamic stability analysis has been conducted, which indicates the occurrence of instabilities due to flow choking effects in both forward and aft thrust bearings. A simple criterion for the onset of axial rotor oscillations has been established and subsequently verified in a micro-turbocharger experiment. The predicted frequencies of the unstable axial oscillations compare well with the experimental measurements.

Rotordynamic and Bearing Upgrade of a High-Speed Turbocharger

2002 ◽  
Vol 125 (1) ◽  
pp. 95-101 ◽  
Author(s):  
B. C. Pettinato ◽  
P. DeChoudhury
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Experimental Results ◽  
Thrust Bearings ◽  
Vibration Data ◽  
Oil Leakage ◽  
Bearing Life ◽  
Thrust Load

The paper discusses the redesign of a high-speed turbocharger for improved bearing life and mechanical operation. The bearings were changed from a pair of combination journal/thrust bearings to a pair of redesigned journal bearings with double acting thrust bearing at the center of the unit. Internal oil passages, drain cavities, and seals were also revised. These modifications resulted in reduced oil leakage across end seals, reduced coke buildup at the turbine, increased thrust load capacity, and improved rotordynamics. Both the analytical and experimental results, which consisted of bearing performance and vibration data of original and modified systems are presented.

Thermohydrodynamic Design Charts for Tilting-Pad Journal Bearings

1996 ◽  
Vol 118 (1) ◽  
pp. 232-238 ◽  
Author(s):  
M. Fillon ◽  
M. Khonsari
Keyword(s):  
Boundary Conditions ◽  
Temperature Rise ◽  
Effective Temperature ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Experimental Measurements ◽  
Design Chart ◽  
Design Charts ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

Design charts are presented which allow one to predict the maximum temperature and a realistic effective temperature of five-shoe tilting-pad bearings. The charts utilize two dimensionless parameters which characterize the temperature rise in the film based on the ISOADI boundary conditions. A number of examples are presented to illustrate the utility of the design chart where the results are compared to both experimental measurements and full THD simulations.

Dynamic Characteristics of Aerostatic Thrust Bearings with Porous Inserts

1980 ◽  
Vol 22 (2) ◽  
pp. 55-58 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Perturbation Method ◽  
Dynamic Characteristics ◽  
Dynamic Behaviour ◽  
Thrust Bearing ◽  
Thrust Bearings ◽  
First Order ◽  
Design Variables ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
First Order Perturbation

A first-order perturbation method is adopted to find the dynamic behaviour of an aerostatic circular thrust bearing having a central porous insert as a restrictor. The linearized gas film stiffness and damping are derived and used to study their behaviour with other design variables.

Rotordynamic and Bearing Upgrade of a High-Speed Turbocharger

2001 ◽  
Author(s):  
Brian C. Pettinato ◽  
Pranabesh DeChoudhury
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Flow Distribution ◽  
Journal Bearings ◽  
Original Design ◽  
Thrust Bearings ◽  
Vibration Data ◽  
Bearing Life ◽  
Oil Flow

The paper discusses the redesign of a high-speed turbocharger for improved bearing life and mechanical operation. The modifications resulted in reduced oil leakage across the end seal, reduced coke buildup at the turbine, increased thrust load capacity, and improved rotordynamics. In particular, rotordynamic stability was improved by eliminating subsynchronous vibration at the operating speed. The redesign consisted of changing the bearings from a pair of combination journal/thrust bearings to a pair of journal bearings and a double acting thrust bearing at the center of the unit. The active thrust bearing was moved away from the hot turbine end of the machine. The thrust bearing geometry was modified for increased minimum film thickness, reduced metal temperature, and increased load capacity. Inlet and drain passages were revised for better oil flow distribution. Unit rotordynamics were improved by upgrading the journal bearings from three-axial-groove to three-lobe design. The upgraded unit kept the same footprint as the original design with only piping modifications required. Extensive analysis and testing were conducted. Testing of the original and revised turbochargers showed improvements in the redesign with reduced bearing metal temperatures and improved rotordynamic stability. Theoretical results along with test data consisting of bearing performance and vibration data of the original and modified system are presented in this paper.

A Rotordynamic, Thermal, and Thrust Load Performance Gas Bearing Test Rig and Test Results for Tilting Pad Journal Bearings and Spiral Groove Thrust Bearings

2016 ◽  
Author(s):  
Aaron M. Rimpel ◽  
Giuseppe Vannini ◽  
Jongsoo Kim
Keyword(s):  
Thrust Bearing ◽  
Journal Bearings ◽  
Temperature Gradients ◽  
Spiral Groove ◽  
Test Rig ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Gas Bearing ◽  
Thrust Load ◽  
Tilting Pad Journal Bearings

A high speed gas bearing test rig was developed to characterize rotordynamic, thermal, and thrust load performance of gas bearings being developed for an oil-free turboexpander. The radial bearings tested in this paper were tilting pad journal bearings with radial compliance features that allow the bearing bore to increase to accommodate shaft growth, and the thrust bearings were a spiral groove type with axial compliance features. The thrust bearing accounts for over 90% of the combined bearing power consumption, which has a cubic relationship with speed and increases with case pressure. Radial bearing circumferential pad temperature gradients increased approximately with speed to the fourth or fifth power, with slightly higher temperature rise for lower case pressure. Maximum steady state bearing pad temperatures increase with increasing speed for similar cooling mass flow rates; however, only the thrust bearing showed a significant increase in temperature with higher case pressure. The thrust bearings were stable at all speeds, but the load capacity was found to be lower than anticipated, apparently due to pad deformations caused by radial temperature gradients in the stator. More advanced modeling approaches have been proposed to better understand the thrust bearing thermal behavior and to improve the thrust bearing design. Finally, the radial bearings tested were demonstrated to be stable up to the design speed of 130 krpm, which represents the highest surface speed for tilting pad gas bearings tested in the literature.

scholarly journals Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

1995 ◽  
Vol 2 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Yu Lie ◽  
R.B. Bhat
Keyword(s):  
Load Distribution ◽  
Thrust Bearing ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Static Deflection ◽  
Analysis Method ◽  
Coupled Dynamics ◽  
Thrust Bearings ◽  
Rotordynamic Coefficients ◽  
Rotor Journal

The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distribution of journal bearings and the static deflection of the rotor and delays the instability of the system considerably in lateral shaft vibration.

Design Charts for Optimum Bearing Configurations: 1—The Full Journal Bearing

1971 ◽  
Vol 93 (2) ◽  
pp. 302-305 ◽  
Author(s):  
H. Moes ◽  
R. Bosma
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Bearings ◽  
Design Chart ◽  
Design Charts ◽  
Dimensionless Groups

This paper presents a new design chart for the full journal bearing using dimensionless groups containing all relevant parameters the designer is mainly interested in. Some illustrative examples of how to use this chart have been added. The main object, however, is the introduction of a new way of presenting bearing data of all kinds of hydrodynamic bearings in such a way that they are directly suitable for design purposes. Particular attention has been paid to the possibility of optimization procedures which follow logically and directly from this chart. Other types of film bearings shall be treated in later papers.

scholarly journals Numerical analysis and experimental research on load carrying capacity of water-lubricated tilting-pad thrust bearings

2018 ◽  
Vol 19 (2) ◽  
pp. 201 ◽  
Author(s):  
Xiuli Zhang ◽  
Gengyuan Gao ◽  
Zhongwei Yin ◽  
Yanzhen Wang ◽  
Chao Gao
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Optimization Method ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Lubrication Regime ◽  
Tilting Pad ◽  
Load Carrying ◽  
Minimum Film Thickness

Water-lubricated bearings are expected to be widely used because of convenience, green, safe and energy saving. The purpose of this study is to investigate the load carrying property of water-lubricated tilting-pad thrust bearings. A large amount of numerical analyses are undertaken based on computational fluid dynamics and the optimization method of pivot location and the calculation method of minimum film thickness are summarized. A thrust bearing is designed according to the numerical results and is tested by experiments. The experimental results validate the numerical method and the minimum film thickness to surface roughness ratio corresponding to the change of bearing lubrication regime from mixed lubrication to hydrodynamic lubrication is obtained.

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