Load Capacity of a Grooved Circular Step Thrust Bearing

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
M. Zakir Hossain ◽  
M. Mahbubur Razzaque
Keyword(s):  
Inclination Angle ◽  
Power Loss ◽  
Parametric Analysis ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Groove Depth ◽  
Step Height ◽  
Bearing Surface ◽  
Pumping Power ◽  
Minimum Film Thickness

A parametric analysis based on narrow groove theory (NGT) has been presented for estimating the load capacity of a grooved circular step thrust bearing. Three types of grooving arrangements of the bearing surface, namely, (a) both the step and the recess are grooved, (b) only the step is grooved, and (c) only the recess is grooved, are considered. It is found that grooving in the step provides the most significant enhancement on the load capacity. The load capacity and the pumping power loss are affected by the step location, step height, and inertia. There is no benefit of making step location smaller than 0.6 that corresponds to the minimum power loss due to pumping. At a very large value of step location, say 0.85, the load capacity drops drastically. To take advantage of inertia as well as grooving, the dimensionless step location should be 0.6 ∼ 0.85 and the dimensionless step height should be less than 5. The load capacity also depends on groove geometry parameters such as groove inclination, groove depth, and fraction of area grooved. The groove inclination angle has been found to be the most important parameter that determines the increase or decrease in load capacity. For the most enhancement of load capacity, the inclination angle should be 135 deg with the direction of rotation, the groove depth should be at least twice the minimum film thickness, and the fraction of the step surface area grooved should be around 0.5.

Effects of Grooving in a Hydrostatic Circular Step Thrust Bearing With Porous Facing

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
M. Mahbubur Razzaque ◽  
M. Zakir Hossain
Keyword(s):  
Mathematical Model ◽  
Inclination Angle ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Maximum Load ◽  
Seepage Flow ◽  
Groove Depth ◽  
Small Thickness ◽  
Flow Through ◽  
High Level

Effects of grooving in a porous faced hydrostatic circular step thrust bearing are investigated using a mathematical model based on the narrow groove theory (NGT). It is shown that enhancement of load capacity by grooving the step is possible at moderate level of permeability of the porous facing. Load capacity drops sharply with the increase of porous facing thickness. However, this drop in load capacity occurs mostly within a small thickness of the porous facing. Considering the coupled effects of permeability and inertia, it is recommended that the dimensionless step location should be 0.5–0.8 and the dimensionless step height should be less than five to take advantage of grooving. The groove geometric parameters such as groove inclination angle, fraction of grooved area and groove depth corresponding to the maximum load capacity are found to be the same for both with and without porous facing. However, with porous facing, the sensitivity of the load capacity on the groove parameters reduces. At high level of permeability, the effects of grooves may become insignificant because of high seepage flow through the porous facing.

Effects of Grooving in a Circular Step Thrust Bearing

2005 ◽  
Author(s):  
M. Mahbubur Razzaque ◽  
M. Zakir Hossain
Keyword(s):  
Pressure Distribution ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Maximum Load ◽  
Outer Radius ◽  
Hydrodynamic Load ◽  
Bearing Surface ◽  
Lubricant Flow ◽  
Inner Radius ◽  
Minimum Film Thickness

Assuming narrow grooves and considering inertia effect, an equation for the pressure distribution in a grooved circular step thrust bearing has been derived. A parametric study has been performed to investigate the effects of step and groove geometry on pressure distribution, load capacity and lubricant flow rate. Three arrangements of the bearing surface have been studied and it has been found that the maximum load capacity is obtained by putting grooves only on the step. Inertia significantly affects the load capacity. To get increased load capacity with increase of inertia, the step inner radius should be larger than 0.45 times of the outer radius. For the most enhancement of hydrodynamic load, the groove inclination angle should be 135° with the direction of rotation and the depth should be twice the minimum film thickness.

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.

The Influence of Ambient Pressure on the Measured Load Capacity of Bump-Foil and Spiral-Groove Gas Thrust Bearings at Ambient Pressures up to 69 Bar on a Novel High-Pressure Gas Bearing Test Rig

2019 ◽  
Author(s):  
Jason Wilkes ◽  
Ryan Cater ◽  
Erik Swanson ◽  
Kevin Passmore ◽  
Jerry Brady
Keyword(s):  
Power Loss ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Ambient Pressure ◽  
Spiral Groove ◽  
Test Rig ◽  
Thrust Bearings ◽  
Order Of Magnitude ◽  
Foil Thrust Bearing ◽  
Thrust Load

Abstract This paper will show the influence of ambient pressure on the thrust capacity of bump-foil and spiral-groove gas thrust bearings. The bearings were operating in nitrogen at various pressures up to 69 bar, and were tested to failure. Failure was detected at various pressures by incrementally increasing the thrust load applied to the thrust bearing until the bearing was no longer thermally stable, or until contact was observed by a temperature spike measured by thermocouples within the bearing. These tests were performed on a novel thrust bearing test rig that was developed to allow thrust testing at pressures up to 207 bar cavity pressure at 260°C while rotating at speeds up to 120,000 rpm. The test rig floats on hydrostatic air bearings to allow for the direct measurement of applied thrust load through linkages that connect the stationary thrust loader to the rotor housing. Test results on a 65 mm (2.56 in) bump-foil thrust bearing at 100 krpm show a marked increase in load capacity with gas density, which has not previously been shown experimentally. Results also show that the load capacity of a similarly sized spiral-groove thrust bearing are relatively insensitive to pressure, and supported an order-of-magnitude less load than that observed for the bump-foil thrust bearing. These results are compared with analytical predictions, which agree reasonably with the experimental results. Predicted power loss is also presented for the bump-foil bearing; however, measured power loss was substantially higher.

The Stepped Thrust Bearing—A Solution by Relaxation Methods

1954 ◽  
Vol 21 (1) ◽  
pp. 19-24
Author(s):  
C. F. Kettleborough
Keyword(s):  
Thrust Bearing ◽  
Load Capacity ◽  
Analytical Investigation ◽  
Alternative Solution ◽  
Bearing Surface ◽  
Relaxation Methods

Abstract Analytical investigation into the stepped thrust bearing was first carried out by Lord Rayleigh, whose solution neglected side leakage. More recently Archibald has presented a solution with side leakage not neglected but limited by the step being straight across the bearing surface perpendicular to the direction of motion. This paper gives an alternative solution, using relaxation methods, which is applicable to any shape of the step. Results show that the load capacity of the completely internal step is much greater than that for the simple tilting slider.

Hydrodynamic Analysis of Hydrostatic Bearings With Runner Misalignment and Pad Damage

2013 ◽  
Author(s):  
Timothy Dimond ◽  
David Barnes
Keyword(s):  
Film Thickness ◽  
Analytical Solutions ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Element Solution ◽  
Flow Loop ◽  
Hydrodynamic Analysis ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings ◽  
Minimum Film Thickness

Hydrostatic bearings are used in applications where surface speeds are low, or viscosities are insufficient to develop significant load capacity due to shear flow. They are also used in jacking applications for initial liftoff of rotors under low or no rotation conditions, especially for heavy rotors where significant babbitt damage would otherwise occur. Traditional hydrostatic bearing analyses assume isothermal lubricating flows. Analytical solutions also assume that the pressure in the pocket of the hydrostatic bearing is constant. This assumption is only approximately correct for low and zero operating speeds. Analytical solutions also assume that the runner and pad surfaces are parallel. The analytical solutions are not capable of capturing damage or misalignment effects. This paper describes a hydrodynamic analysis of a hydrostatic thrust bearing. The solution is based on a finite element solution to the generalized Reynolds equation. The finite element solution is applied in both the pocket and pad regions of the hydrostatic bearings. The analysis includes a flow loop balance that considers the effects of pressure losses in the lubricant supply piping, allowing for modeling of saturation effects in bearing load capacity. The flow loop balance for the lubrication supply is coupled with the bearing solution. This allows for pad loads to vary as a function of circumferential position in thrust bearings. The analysis was applied to the operation of a hydrostatic thrust bearing system for the HUSIR radio telescope at the Massachusetts Institute of Technology. Simplified models of pad damage and runner misalignment were considered in the analysis. The minimum film thickness and pressure profile was calculated. Runner misalignment reduced minimum film thickness by up to 80% when compared to a parallel runner under identical loading conditions. Runner damage equivalent to twice the nominal film thickness reduced the minimum film thickness by approximately 10%.

Application of Materials on Foil Thrust Bearings for Micro Turbines

2011 ◽  
Vol 201-203 ◽  
pp. 2759-2762
Author(s):  
Quan Zhou ◽  
Yu Hou ◽  
Ru Gang Chen
Keyword(s):  
Thrust Bearing ◽  
Load Capacity ◽  
Bearing Surface ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Soft Surface ◽  
Static Part ◽  
Micro Turbine ◽  
Foil Thrust Bearing

Foil bearing that has a soft surface is a kind of air bearing. The performances of foil bearings are greatly affected by the materials of bearing surface, which is called foil element. In order to estimate the performance of foil bearings, two kinds of foil thrust bearings that are made of different materials respectively were tested in a micro turbine system, which contains rotation part and static part. Load capacity and stability of these foil thrust bearings were investigated in experiments. The results show that bearing which contains rubber has higher load capacity and bearing which contains copper foil has higher stability. According to the work in this paper, applications with different requirements can adopt suitable foil thrust bearing.

Performance of textured spherical thrust hybrid bearing operating with shear thinning and piezoviscous lubricants

2021 ◽  
pp. 135065012110313
Author(s):  
Nitin Agrawal ◽  
Satish C Sharma
Keyword(s):  
Power Loss ◽  
Reynolds Equation ◽  
Thrust Bearing ◽  
Strong Dependence ◽  
Shear Thinning ◽  
Flow Equation ◽  
Textured Surfaces ◽  
Bearing Surface ◽  
Fluid Film Bearings ◽  
Hybrid Bearing

Improving the lubricating performance of tribo-pairs using engineering textured surfaces has been the main focus of tribology research in recent years. The use of a suitably designed micro-texture on the bearing surface may have a beneficial effect on the performance of fluid film bearings. In the present paper, a mathematical model of a hybrid spherical thrust bearing is developed considering the effect of shear thinning and piezoviscous behaviour of a lubricant. The modified Reynolds equation for a hybrid spherical thrust bearing configuration together with a restrictor flow equation for a capillary restrictor is solved using a finite-element method. In this work, the effect of various micro-textures shapes (spherical, circular, conical and square) and non-Newtonian lubricant behaviour having shear thinning and piezoviscous effects are analysed. The numerically simulated result shows a strong dependence on the combined effect of shear thinning and piezoviscous lubricant behaviour and a chosen geometric shape of a texture. The frictional power loss is seen to reduce nearly by 24.05%, and the stiffness gets enhanced by 11.08%.

The Steady-State Characteristics of a Hydrostatic Thrust Bearing With a Floating Disk

1989 ◽  
Vol 111 (2) ◽  
pp. 352-357
Author(s):  
M. Harada ◽  
J. Tsukazaki
Keyword(s):  
Steady State ◽  
Rotational Speed ◽  
Power Loss ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Frictional Torque ◽  
Thrust Bearings ◽  
Stable Position ◽  
Surface Configuration

To reduce the frictional power loss of hydrostatic thrust bearings, the hydrostatic thrust bearing with a floating disk shaped in a simplified configuration is proposed. And the load capacity and the frictional torque are experimentally investigated in laminar and superlaminar regimes. Following results can be obtained: (1) The disk floats at a certain stable position for given shaft rotational speed and rotates at nearly half rotational speed of the shaft. (2) The frictional torque of this type of the bearing is less than half of a conventional hydrostatic thrust bearing with the same surface configuration as the floating disk.

Influence of Turbulence on Performance Characteristics of the Tilting Pad Thrust Bearing

1974 ◽  
Vol 96 (1) ◽  
pp. 110-116 ◽  
Author(s):  
J. W. Capitao
Keyword(s):  
Turbulent Flow ◽  
Power Loss ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Equal Area ◽  
Thrust Bearings ◽  
Finite Difference Equations ◽  
Tilting Pad ◽  
Oil Flow ◽  
Flow Theories

The influence of fluid film turbulence on the performance of centrally-pivoted tilting pad thrust bearings was analyzed. Major features of the analysis are: (1) today’s two predominant “engineering” turbulent flow theories are delineated and their quantitative predictions compared; (2) a spherical pad profile was assumed, and (3) an equal area technique was used in the finite difference equations. The results confirmed earlier predictions of increases in power loss and load capacity when compared to a laminar solution. Also, no significant differences were found between the results predicted by the two predominant turbulent flow theories. Power loss, load capacity, and hydrodynamic oil flow are given for 13, 15, and 17 in. sizes. Comparisons of laminar and turbulent numerical results are presented.

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