Thermal Wedge Lubrication of Parallel Surface Thrust Bearings

1965 ◽  
Vol 87 (4) ◽  
pp. 823-830 ◽  
Author(s):  
I. G. Currie ◽  
C. A. Brockley ◽  
F. A. Dvorak
Keyword(s):  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Performance Comparison ◽  
Superior Performance ◽  
Stable Operation ◽  
Parallel Surface ◽  
Tilting Pad ◽  
Performance Curves ◽  
Load Carrying

The parallel surface thrust bearing has been studied both theoretically and experimentally. The general equations governing the laminar flow of a Newtonian fluid are presented and suitably reduced to describe the flow of lubricant through a plain collar bearing with sector pads. A computer solution of the resulting equations has been obtained in which the variations of density and viscosity with temperature are accommodated and the circumferential leakage of oil from the bearing is recognized. The resulting performance curves indicate that useful load-carrying capacities, produced by a “thermal wedge” effect, are possible with a parallel surface thrust bearing. The effect of the inlet oil temperature and bearing speed on the performance is shown. Tests were carried out on three, four, and five-pad bearings operating at 15,000 rpm. It was found that circumferential oil seals were required to insure stable operation. The results confirm that hydrodynamic lubrication may be achieved with a parallel surface thrust bearing. However, it was found that some practical limitations are imposed by high temperatures. A comparison between the theoretical load capacity of an optimum tilting pad bearing and that of a parallel surface bearing for equivalent pad dimensions, speed, and lubricant conditions revealed that the tilting pad bearing had the superior performance. Comparison of friction results with the findings of other workers shows good agreement.

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.

On the Significance of the Inlet Pressure Build-Up in the Design of Tilting-Pad Bearings

1990 ◽  
Vol 112 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Cz. M. Rodkiewicz ◽  
K. W. Kim ◽  
J. S. Kennedy
Keyword(s):  
Thrust Bearing ◽  
Ambient Pressure ◽  
Inlet Pressure ◽  
Load Carrying Capacity ◽  
Integral Theorem ◽  
Lubricating Film ◽  
Tilting Pad ◽  
Load Carrying ◽  
Momentum Integral ◽  
Entrance Pressure

An operating tilting-pad thrust bearing generates a fore-region which is responsible for maintaining, at the bearing entrance, a pressure which is higher than the ambient pressure. This entrance pressure, in the presented analysis, is obtained by applying to the fore-region the momentum integral theorem. The solution of the lubricating film region is then obtained by using this modified inlet pressure. This solution yields the pressure distribution, the load carrying capacity, the film ratio and the frictional force for several values of the modified Reynolds number and various pivot positions. The analysis shows that there is a significant influence of the fore-region pressure on the bearing performance and that to properly design efficient tilting-pad bearing this effect should be taken into consideration.

On the performance of foil thrust bearing with misaligned bearing runner

2017 ◽  
Vol 69 (2) ◽  
pp. 105-115 ◽  
Author(s):  
Abdelrasoul M. Gad
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Approximation Technique ◽  
Hydrodynamic Effect ◽  
Stable Operation ◽  
Content Type ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Foil Thrust Bearing ◽  
Stiffness And Damping

Purpose Compliant foil thrust bearings are promising bearings for high-speed oil-free turbomachinery. However, most previous experimental and numerical approaches to investigate the performance of these bearings have ignored the effect of bearing runner misalignment. Therefore, this paper aims to evaluate the effects of static and dynamic angular misalignments of the bearing runner on the performance of a gas-lubricated foil thrust bearing. Design/methodology/approach The bearing runner is allowed a maximum angular misalignment that produces a minimum gas film thickness as low as 20 per cent of the nominal clearance. Then, the variations of bearing load carrying capacity, viscous power loss and stiffness and damping coefficients of the gas film with runner misalignment are thoroughly analyzed. The flow in the gas film is modeled with compressible Reynolds equation along with the Couette approximation technique, and the deformation of the compliant bearing is calculated with a robust analytical model. Small perturbations method is used to calculate the force and moment dynamic coefficients of the gas film. Findings The results show that misaligned foil thrust bearings are capable of developing a restoring moment sufficient enough to withstand the imposed misalignments. Furthermore, the enhanced hydrodynamic effect ensures a stable operation of the misaligned bearing, and the results highlighted the role of the compliant bearing structure to maintain foil bearing prominent features even at misaligned conditions. Originality/value The value of this study is the evaluation of the effects of runner angular misalignments on the static and dynamic characteristics of Generation II bump-type foil thrust bearing.

Measurements of Static and Dynamic Load Performance of a 102 mm Carbon-Graphite Porous Surface Tilting-Pad Gas Journal Bearing

2021 ◽  
Author(s):  
Luis San Andrés ◽  
Rachel Bolen ◽  
Jing Yang ◽  
Ryan McGowan
Keyword(s):  
Dynamic Load ◽  
Load Capacity ◽  
Stable Operation ◽  
Specific Load ◽  
Force Coefficients ◽  
Supply Pressure ◽  
Air Supply ◽  
Tilting Pad ◽  
Frequency Independent ◽  
Gas Bearing

Abstract Aerostatic journal bearings with porous tilting pads enable shaft support with minute drag power losses. To date archival information on the static and dynamic load performance of this bearing type is scant. Thus, the paper presents measurements conducted with an air lubricated bearing with diameter d = 102 mm and comprising four tilting pads made of porous carbon-graphite, each with length L = 76 mm. Two nested Belleville washers resting on spherical pivots support each pad. At ambient temperature of ∼ 21°C, as the air supply pressure into the bearing pads increases, so does the bearing aerostatic specific load (F/(L·d)) that reaches 58% of the pressure difference, supply minus ambient. With an air supply pressure of 7.8 bar(a), the test bearing static stiffness KS = 13.1 MN/m, is independent of both shaft speed and static load. KS is just 63% of the washers’ stiffness KP = 20.6 MN/m (during loading). While operating with shaft speeds equal to 6 krpm and 9 krpm (150 Hz) and under specific loads to 115 kPa and 101 kPa respectively, dynamic load experiments with excitation frequencies up to 342 Hz show the test bearing supplied with air at 7.8 bar(a) has frequency independent stiffness (K) and damping (C) coefficients. For rotor speeds equaling 0, 6 and 9 krpm, the bearing direct stiffnesses KXX ∼ KYY range from 13.6 MN/m to 32.7 MN/m as the specific load increases from 0 kPa to 115 kPa. The direct damping coefficients CXX ∼ CYY are as large as 5.8 kN·s/m, though having a large experimental uncertainty. Bearing cross-coupled force coefficients are insignificant. The test porous gas bearing reached its intended load capacity, demonstrated a dynamically stable operation and produced force coefficients mainly affected by the pads’ pivot supports and the magnitude of air supply pressurization.

Fluid Film Lubrication of Parallel Thrust Surfaces

1946 ◽  
Vol 155 (1) ◽  
pp. 49-67 ◽  
Author(s):  
A. Fogg
Keyword(s):  
Thrust Bearing ◽  
Fluid Film ◽  
Load Carrying Capacity ◽  
Low Friction ◽  
Metallic Contact ◽  
Tilting Pad ◽  
Load Carrying ◽  
Parallel Surfaces ◽  
Film Lubrication ◽  
Fluid Film Lubrication

During the course of an investigation into the general characteristics of various types of thrust bearing, it has been shown that opposed parallel surfaces, under certain conditions of operation, have a load carrying capacity approaching that of tilting pad bearings of the Michell type and of the same bearing area. Considerable evidence has been obtained, such as the low friction losses, the dependence of coefficient of friction on viscosity, speed and load, and the apparent absence of metallic contact, which strongly indicates that these bearings operate under fluid film conditions. Their performance does not seem to depend on a rounded inlet edge, and the apparent establishment of fluid film conditions without the usually accepted requirement of convergence of the bearing surfaces is regarded as a new phenomenon in lubrication. A tentative theory on broad lines is suggested as an explanation of the behaviour.

Paper 17: A Self-Acting Parallel Surface Thrust Bearing

1967 ◽  
Vol 182 (14) ◽  
pp. 139-146 ◽  
Author(s):  
A. H. Bennett ◽  
C. Ettles
Keyword(s):  
Thrust Bearing ◽  
Flat Surface ◽  
Operating Conditions ◽  
Superior Performance ◽  
Land Type ◽  
Thrust Bearings ◽  
Parallel Surface ◽  
Analysis Design ◽  
Design And Testing ◽  
Good Agreement

This paper describes the analysis, design, and testing of a one-piece hydrodynamic thrust bearing with an initially flat surface, which has a performance similar to conventional pivoted pad thrust bearings. The leading portion of each pad is undercut allowing it to deflect elastically under load and form a wedge-shaped film. Analysis of the configuration used is particularly simple and gives good agreement with experimental results. This cantilever bearing is compared quantitatively with the plain land type and is shown to have a greatly superior performance. Comprehensive instrumentation mounted in both the rotor and the bearing gave an accurate account of the operating conditions.

scholarly journals Theoretical Disquisition on the Static and Dynamic Characteristics of an Adaptive Stepped Hydrostatic Thrust Bearing with a Displacement Compensator

Mathematics ◽  
2021 ◽  
Vol 9 (22) ◽  
pp. 2949
Author(s):  
Vladimir Kodnyanko ◽  
Andrey Kurzakov ◽  
Olga Grigorieva ◽  
Maxim Brungardt ◽  
Svetlana Belyakova ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Metal Cutting ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Theoretical Research ◽  
Stable Operation ◽  
Adaptive Function ◽  
Main Bearing ◽  
Thrust Bearings ◽  
Wide Range

Stepped hydrostatic thrust bearings used in metal-cutting machines are characterized by high load capacity and damping, which ensure the stable operation of structures. However, in comparison with throttle thrust bearings, they have a high compliance. It is preferable that, in addition to the main bearing function, a modern hydrostatic bearing has the ability to provide low (including negative) compliance for the implementation of an adaptive function in order to actively compensate for the deformation of the machine resilient system, thereby increasing the accuracy of metalworking. This paper considers the design of a stepped hydrostatic thrust bearing, which, in order to reduce the compliance to negative values, features a technical improvement consisting of the use of an active displacement compensator on an elastic suspension. In this paper, the results of mathematical modeling and theoretical research of stationary and non-stationary modes of operation of the adaptive thrust bearing are presented. The possibility of a significant reduction in the static compliance of the structure, including the negative compliance values, is shown. It was found that negative compliance is provided in a wide range of loads, which can be up to 80% of the range of permissible bearing loads. The study of the dynamic characteristics showed that with a targeted selection of parameters that ensure optimal performance, the adaptive thrust bearing is able to operate stably in the entire range of permissible loads. It has been established that an adaptive stepped hydrostatic thrust bearing with a displacement compensator has a high stability margin, sufficient to ensure its operability when implementing the adaptive function.

scholarly journals Appearance of Hysteresis Phenomena on Hydrodynamic Lubrication in a Seal-Type Thrust Bearing with Dimples

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5222
Author(s):  
Reo Miwa ◽  
Norifumi Miyanaga ◽  
Jun Tomioka
Keyword(s):  
Carrying Capacity ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Frictional Torque ◽  
Hysteresis Phenomenon ◽  
Load Carrying Capacity ◽  
Cavitation Bubbles ◽  
Load Carrying ◽  
The Difference ◽  
Hysteresis Phenomena

This paper described unique hysteresis phenomena that appear in the hydrodynamic lubrication properties of dimpled thrust bearings. A seal-type thrust bearing specimen was textured with dimples. The load-carrying capacity and frictional torque were measured with a constant film thickness and compared to those of a dimple-free specimen. For examining the size of cavitation bubbles that occurred in various conditions, the lubricating area was observed during experiments. The used dimpled specimen produced the load-carrying capacity, and it exhibited an interesting hysteresis phenomenon, the difference in the values in the increasing and decreasing processes of rotational speed. The visualization test results revealed that the size of cavitation bubbles occurring within the dimples strongly affected this phenomenon. In addition, the dimpled specimen was able to reduce the frictional torque compared to the dimple-free specimen. However, the frictional torque did not show the hysteresis loop similar to that shown in the load-carrying capacity.

scholarly journals Nanofluids for Performance Improvement of Heavy Machinery Journal Bearings: A Simulation Study

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2120 ◽  
Author(s):  
Hamid Sadabadi ◽  
Amir Sanati Nezhad
Keyword(s):  
Carrying Capacity ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Computational Simulation ◽  
Weight Fraction ◽  
Journal Bearings ◽  
Load Carrying Capacity ◽  
Inorganic Fullerene ◽  
Aggregation Effect ◽  
Load Carrying

Nanofluids have extensive applications in hydrodynamic journal bearings used in heavy industry machinery. Inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2 NPs) are the most common additive for lubrication purpose due to their excellent mechanical characteristics along with their effect on reducing friction and wear. In this work, a computational simulation approach with discrete phase modeling (DPM) of suspended nanoparticles was used to evaluate the application of the IF-WS2 nanofluid lubricant on load carrying capacity of high-load journal bearings where the normal loads are high, considering the bearing dimensions. For accurate simulation, nanofluid viscosity was calculated considering the aggregation effect of NPs by using scanning electron microscopy (SEM) imaging of the nanofluids. A benchmark study was first performed to assess the model accuracy. Hydrodynamic lubrication was simulated under different nanofluid weigh fractions. The simulated pressure distribution was then employed to determine the load capacity of the bearing. The results show an approximately 20% improvement of load carrying capacity at 5% weight fraction of WS2-oil nanofluid.

The Dual Action Gas Thrust Bearing—A New High Load Bearing Concept

1977 ◽  
Vol 99 (1) ◽  
pp. 89-94
Author(s):  
I. Etsion
Keyword(s):  
Numerical Solution ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Load Capacity ◽  
High Load ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Dual Action ◽  
Hydrodynamic Effects

The principle of utilizing hydrodynamic effects in diverging films for improving load capacity in gas thrust bearings is discussed. A new concept of dual action bearing based on that principle is described and analyzed. The potential of the new bearing is demonstrated both analytically for an infinitely long slider and by numerical solution for a flat sector shaped thrust bearing. It is shown that the dual action bearing can extend substantially the range of load carrying capacity in gas lubricated thrust bearings and improve their efficiency.

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