Discussion: “A Class of Maximum Load Capacity Sector Thrust Bearings” (Gregory, E. W., and Maday, C. J., 1977, ASME J. Lubr. Technol., 99, pp. 180–184)

1977 ◽  
Vol 99 (2) ◽  
pp. 184-184
Author(s):  
I. Etsion
Keyword(s):  
Load Capacity ◽  
Maximum Load ◽  
Thrust Bearings

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.

Design Optimization of Gas Foil Thrust Bearings for Maximum Load Capacity

2015 ◽  
Author(s):  
Tae Ho Kim ◽  
Tae Won Lee
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Load Capacity ◽  
Maximum Load ◽  
Drag Torque ◽  
Rotor Speed ◽  
Design Guideline ◽  
Film Pressure ◽  
Thrust Bearings ◽  
Minimum Film Thickness

Improvement of the load capacity of gas foil thrust bearings (GFTBs) is important to broadening their application in oil-free microturbomachinery (<250 kW) with high power density. Although GFTBs have the significant advantage of low friction without the use of lubrication systems compared to oil film thrust bearings, their inherently low load capacity has limited their application. The aim of the present study was to develop a design guideline for increasing the load capacity of GFTBs. The Reynolds equation for an isothermal isoviscous ideal gas was used to calculate the gas film pressure. To predict the ultimate load capacity of the GFTB, the pressure was averaged in the radial direction of the gas flow field used to deflect the foil structure. The load capacity, film pressure profile, and film thickness profile were predicted for a GFTB with an outer radius of 55 mm, inner radius of 30 mm, and eight foils each of arc length 45°. The predictions showed that the load capacity of the GFTB increased with increasing rotor speed and decreasing minimum film thickness, and was always lower than the analytically determined limit value for infinite rotor speed (obtained by simple algebraic equations). A parametric study in which the ramp extent (or inclined angle) was increased from 5° to 40°, and the ramp height from 0 to 0.320 mm, revealed that the GFTB had an optimal ramp extent of ∼22.5° and ramp height of ∼0.030 mm for maximum load capacity. Interestingly, the optimal values were also valid for a rigid-surface bearing. The predicted load capacities for a ramp extent of ∼22.5° and increasing ramp height from 0.030 to 0.320 mm were compared with experimental data obtained from a previous work. The predictions for a ramp height of 0.155 mm were in good agreement with the experimental data for all three test GFTBs with outer radii of 45, 50, and 55 mm, respectively. In addition, this paper shows that the predicted drag torque increases linearly with increasing rotor speed and decreasing minimum film thickness, and nonlinearly with decreasing ramp height. The drag torque significantly increased only for ramp heights below the optimal value. The predictions imply that the optimal ramp height improves the load capacity of the GFTB with little change in the drag torque.

Design Optimization of Gas Foil Thrust Bearings for Maximum Load Capacity1

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Tae Ho Kim ◽  
Moonsung Park ◽  
Tae Won Lee
Keyword(s):  
Film Thickness ◽  
Load Capacity ◽  
Maximum Load ◽  
Ideal Gas ◽  
Outer Radius ◽  
Test Results ◽  
Rotor Speed ◽  
Design Guideline ◽  
Film Pressure ◽  
Thrust Bearings

The aim of the present study is to develop a design guideline to improve the load capacity of gas foil thrust bearings (GFTBs). The Reynolds equation for an isothermal isoviscous ideal gas calculates the gas film pressure. The film pressure averaged in the radial direction determines the ultimate load capacity. The load capacity, film pressure profile, and film thickness profile are predicted for a GFTB with an outer radius of 55 mm, inner radius of 30 mm, and eight foils each of arc length 45 deg. The predictions show that the load capacity of the GFTB increases with increasing rotor speed and decreasing minimum film thickness. A parametric study, in which the ramp extent (or inclined angle) is increased from 5 deg to 40 deg, and the ramp height from 0 to 320 μm, reveals that GFTBs have an optimal ramp extent of ∼22.5 deg and ramp height of 30 μm for maximum load capacity. A series of maximum load capacity measurements are conducted on four test GFTBs with ramp heights of 50, 150, 250, and 350 μm at the speeds of 12, 15, and 18 krpm. To estimate the maximum load capacity, the applied load is increased until the drag torque rises suddenly with a sharp peak. The test results show that the maximum load capacity generally increases for decreasing ramp height and for increasing rotor speed. The GFTB with a ramp height of 50 μm shows the largest maximum load capacity of 510 N, for example. Test results are in good agreement with model predictions.

Maximum Load Capacity Profiles for Gas Thrust Bearings Working Under High Compressibility Number Conditions

1998 ◽  
Vol 120 (3) ◽  
pp. 571-576 ◽  
Author(s):  
I. Iordanoff
Keyword(s):  
Load Capacity ◽  
Maximum Load ◽  
High Load ◽  
Two Dimensional ◽  
One Dimensional ◽  
Thrust Bearings ◽  
Constant Slope ◽  
Compressibility Effects ◽  
Composite Bearing ◽  
Commercial Equipment

To meet the requirements of new commercial equipment, performances of air thrust bearings always have to be improved. This work is concerned with the research of the converging profile that will give high load capacities. When compressibility effects increase (when the compressibility number Λ is over 50), a one-dimensional study shows that the best bearing is a composite bearing, i.e., one in which the leading portion has a constant slope followed by a surface parallel to the runner. For each compressibility number, entrance film thickness H1 and the transition angle θ1 define the best profile. In a two-dimensional study, for compressibility numbers from 10 to 1000, comparison in term of load capacity is made between tapered and composite profiles. It outlines the better load capacity of the composite bearings and confirms the good results obtained by Heshmat (1983) and Gray (1981) with such profiles.

Thermal Distortion of Spiral-Grooved Gas-Lubricated Thrust Bearings

1971 ◽  
Vol 93 (1) ◽  
pp. 102-111 ◽  
Author(s):  
C. Wachmann ◽  
S. B. Malanoski ◽  
J. H. Vohr
Keyword(s):  
Thrust Bearing ◽  
Load Capacity ◽  
Heat Removal ◽  
Maximum Load ◽  
Thermal Distortion ◽  
Thrust Bearings ◽  
Self Heating ◽  
Worked Example ◽  
Performance Curves

Self-heating during operation causes a bearing to undergo thermal distortion. A method is presented to determine the consequent effects on the load capacity of a spiral-grooved air-lubricated thrust bearing designed for maximum load capacity. The effect of mode of heat removal is discussed. Appropriate performance curves and a worked example are given.

Load Capacity Tests on Tapered-Land and Pivoted-Shoe Thrust Bearings for Large Steam-Turbine Application

1959 ◽  
Vol 81 (2) ◽  
pp. 208-213
Author(s):  
R. E. Brandon ◽  
H. C. Bahr
Keyword(s):  
Bearing Capacity ◽  
Steam Turbine ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Maximum Load ◽  
Full Scale ◽  
Thermal Distortion ◽  
Test Installation ◽  
Land Type ◽  
Thrust Bearings

Results of full-scale maximum load capacity tests on large, 3600-rpm, pivoted-shoe and tapered-land thrust bearings are reported. The results show 700 psi capacity for the pivoted-shoe bearing and 1085 psi for the tapered-land type. Additional evidence of thermal distortion and its effect on thrust-bearing capacity are discussed. A brief description of a new thrust-bearing test installation also is included.

A hydrodynamic lubrication model and comparative analysis for coupled microgroove journal-thrust bearings lubricated with water

2019 ◽  
Vol 234 (11) ◽  
pp. 1755-1770
Author(s):  
Guo Xiang ◽  
Yanfeng Han ◽  
Renxiang Chen ◽  
Jiaxu Wang ◽  
Xiaokang Ni ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Mutual Effect ◽  
Hydrodynamic Pressure ◽  
Isosceles Triangle ◽  
Maximum Load ◽  
Hydrodynamic Effect ◽  
Thrust Bearings ◽  
Lubrication Performance

The novelty of this study is to develop a hydrodynamic lubrication numerical model for coupled microgroove journal-thrust bearings (or coupled bearings) under water-lubricated condition. In the present model, the continuity of the hydrodynamic pressure and the fluid field (or coupled hydrodynamic effect) at common boundary is considered to reveal the mutual effect between the hydrodynamic behavior of the journal bearing and the thrust bearing. The lubrication performances of the coupled microgroove bearing with three bottom shapes, i.e., isosceles triangle, right triangle, and left triangle, are studied comparatively. Additionally, the effects of the microgroove depth on the lubrication performances of the coupled bearing are discussed. The present study reveals that the coupled hydrodynamic effect generated by the coupled bearing can improve the lubrication performance for both the journal and the thrust bearing. The microgroove with left triangle bottom shape yields the optimal lubrication performance as compared to the other two. There is an optimal groove depth that generates the maximum load capacity and the minimum friction coefficient for both the journal and the thrust bearing.

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