Closure to “Discussions of ‘Recent Improvements in Load Capacity of Large-Steam-Turbine Thrust Bearings’” (1961, ASME J. Eng. Power, 83, p. 135)

1961 ◽  
Vol 83 (1) ◽  
pp. 135-136
Author(s):  
H. C. Bahr
Keyword(s):  
Steam Turbine ◽  
Load Capacity ◽  
Thrust Bearings

Recent Improvements in Load Capacity of Large-Steam-Turbine Thrust Bearings

1961 ◽  
Vol 83 (1) ◽  
pp. 130-134 ◽  
Author(s):  
H. C. Bahr
Keyword(s):  
Thermal Conductivity ◽  
Steam Turbine ◽  
Load Capacity ◽  
Full Scale ◽  
High Thermal Conductivity ◽  
Thermal Distortion ◽  
Maximum Capacity ◽  
Thrust Bearings ◽  
Apparent Reduction

The load capacity of tapered-land and pivoted-shoe thrust bearings has been increased significantly by the use of materials with high thermal conductivity and by modified shoe designs. Results of full-scale maximum-capacity tests at 3600 rpm and at 1800 rpm are presented. Improvements in bearing performance have been made possible by an apparent reduction in thermal distortion and bearing temperature.

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.

Identification of Dynamic Characteristics of Gas Foil Thrust Bearings Using Base Excitation

2016 ◽  
Author(s):  
Tae Ho Kim ◽  
Moon Sung Park ◽  
Jongsung Lee ◽  
Young Min Kim ◽  
Kyoung-Ku Ha ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Loss Factor ◽  
Load Capacity ◽  
Excitation Frequency ◽  
Vibrational Amplitude ◽  
Test Rig ◽  
Thrust Bearings ◽  
Bearing Plate ◽  
Bearing Stiffness

Gas foil bearings (GFBs) have clear advantages over oil-lubricated and rolling element bearings, by virtue of low power loss, oil-free operation in compact units, and rotordynamic stability at high speeds. However, because of the inherent low gas viscosity, GFBs have lower load capacity than the other bearings. In particular, accurate measurement of load capacity and dynamic characteristics of gas foil thrust bearings (GFTBs) is utmost important to widening their applications to high performance turbomachinery. In this study, a series of excitation tests were performed on a small oil-free turbomachinery with base excitations in the rotor axial direction to measure the dynamic load characteristics of a pair of six-pad, bump-type GFTBs, which support the thrust collar. An electromagnetic shaker provided dynamic sine sweep loads to the test bench (shaking table), which held rigidly the turbomachinery test rig for increasing excitation frequency from 10 Hz to 200 Hz. The magnitude of the shaker dynamic load, represented as an acceleration measured on the test rig, was increased up to 9 G (gravity). An eddy current sensor installed on the test rig housing measured the axial displacement (or vibrational amplitude) of the rotor thrust collar during the excitation tests. The axial acceleration of the rotor relative to the test rig was calculated using the measured displacement. A single degree-of-freedom base excitation model identified the frequency-dependent dynamic load capacity, stiffness, damping, and loss factor of the test GFTB for increasing shaker dynamic loads and increasing bearing clearances. The test results show that, for a constant shaker force and the test GFTB with a clearance of 155 μm, an increasing excitation frequency increases the dynamic load carried by the test GFTB, i.e., bearing reaction force, until a certain value of the frequency where it jumps down suddenly because of the influence from Duffing’s vibrations of the rotor. The bearing stiffness increases and the damping decreases dramatically as the excitation frequency increases. Generally, the bearing loss factor ranges from 0.5 to 1.5 independent of the frequency. As the shaker force increases, the bearing dynamic load, stiffness, damping, and loss factor increase depending on the excitation frequency. Interestingly, the agreements between the measured GFTB dynamic load versus the thrust runner displacement, the measured GFTB static load versus the structural deflection, and the predicted static load versus the thrust runner displacement are remarkable. Further tests with increasing GFTB clearances of 155, 180, 205, and 225 μm revealed that the vibrational amplitude increases and the jump-down frequency decreases with increasing clearances. The bearing load increases, but the bearing stiffness, damping, and loss factor decrease slightly as the clearance increases. The test results after a modification of the GFTB by rotating one side bearing plate by 30° relative to the other side bearing plate revealed insignificant changes in the dynamic characteristics. The present dynamic performance measurements provide a useful database of GFTBs for use in microturbomachinery.

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.

Influence of Nanoparticles in Lubricants on the Load Capacity of Hydrostatic Thrust Bearings

2012 ◽  
Vol 486 ◽  
pp. 99-103
Author(s):  
Huei Chu Weng ◽  
Yuan Kang
Keyword(s):  
Volume Fraction ◽  
Load Capacity ◽  
Particle Volume Fraction ◽  
Closed Form Solution ◽  
Form Solution ◽  
Interparticle Interaction ◽  
Particle Volume ◽  
Thrust Bearings ◽  
Bearing Load ◽  
Thrust Pad

An analysis for the effect of nanoparticles in lubricants on load capacity is performed to study a rectangular thrust pad hydrostatic bearing with a central recess. The closed-form solution of the bearing load is derived analytically and presented for nanofluids with interparticle interaction. Results reveal that in the presence of nanoparticles, the enhanced viscosity could result in an increase in bearing load; moreover, this increase dramatically increases as particle volume fraction and/or interparticle interaction increases. The effect of nanoparticles on the bearing load can be magnified by decreasing the bearing gap.

Numerical analysis of the dynamic performance of aerostatic thrust bearings with different restrictors

2018 ◽  
Vol 233 (3) ◽  
pp. 406-423 ◽  
Author(s):  
Hailong Cui ◽  
Yang Wang ◽  
Xiaobin Yue ◽  
Yifei Li ◽  
Zhengyi Jiang
Keyword(s):  
Load Capacity ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Dynamic Mesh ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping ◽  
The Impact ◽  
The Relationship

This study utilizes a dynamic mesh technology to investigate the dynamic performance of aerostatic thrust bearings with orifice restrictor, multiple restrictors, and porous restrictor. An experiment, which investigates the bearing static load capacity, was carried out to verify the calculation accuracy of dynamic mesh technology. Further, the impact of incentive amplitude, incentive frequency, axial eccentricity ratio, and non-flatness on the bearing dynamic performance was also studied. The results show incentive amplitude effect can be ignored at the condition of amplitude less than 5% film thickness, while the relationship between dynamic characteristics and incentive frequency presented a strong nonlinear relationship in the whole frequency range. The change law of dynamic stiffness and damping coefficient for porous restrictor was quite different from orifice restrictor and multiple restrictors. The bearing dynamic performance increased significantly with the growth of axial eccentricity ratio, and the surface non-flatness enhanced dynamic performance of aerostatic thrust bearings.

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