Theory of Externally Pressurized Circular Thrust Porous Gas Bearing

1965 ◽  
Vol 87 (3) ◽  
pp. 613-620 ◽  
Author(s):  
H. Mori ◽  
H. Yabe ◽  
T. Ono
Keyword(s):  
Porous Media ◽  
Porous Material ◽  
Pressure Distribution ◽  
Permeability Coefficient ◽  
Load Capacity ◽  
Bearing Surface ◽  
Porous Bearing ◽  
Parallel Flows ◽  
Flow Through ◽  
Gas Bearing

The externally pressurized circular thrust gas bearing with porous bearing surface is analysed here theoretically. The authors use “permeability coefficient” which identifies the characteristic of porous media, and introduce the concepts of the “equivalent clearance” and the “effective restricting thickness” of the porous layer so that the flow through the porous material can be analyzed in both axial and radial directions, and the flow in the porous material and the bearing clearance may be considered as two parallel flows connected with each other. The analysis coincided qualitatively as well as quantitatively with the results of the experiments concerning the pressure distribution and the load capacity.

Static and Dynamic Characteristics of Aerostatic Circular Porous Thrust Bearings (Effect of the Shape of the Air Supply Area)

2000 ◽  
Vol 123 (3) ◽  
pp. 501-508 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kohno
Keyword(s):  
Porous Material ◽  
Dynamic Characteristics ◽  
Thrust Bearing ◽  
Aerostatic Bearing ◽  
Bearing Surface ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Porous Bearing ◽  
Air Supply ◽  
Bearing Design

Recently, graphite porous material has been used successfully in an aerostatic bearing. In actual bearing design, it is often necessary to reduce the thickness of porous material to make the bearing smaller. However, a reduction in thickness results in a reduction in the strength of the porous material. In particular, when the diameter of porous material is large, it is difficult to supply the air through the full pad area of porous material because it deforms. Therefore, in this paper, two types of air supply method (the annular groove supply and the hole supply) in a circular aerostatic porous thrust bearing are proposed to avoid the deflection of the bearing surface. The static and dynamic characteristics of aerostatic porous bearing with these air supply methods are investigated theoretically and experimentally. In addition, the effects of a surface restricted layer on the characteristics are clarified.

A Theory of an Externally Pressurized Circular Thrust Gas Bearing With Consideration of the Effects of Lubricant Inertia

1963 ◽  
Vol 85 (2) ◽  
pp. 304-309 ◽  
Author(s):  
Haruo Mori
Keyword(s):  
Velocity Distribution ◽  
Pressure Distribution ◽  
Elliptic Function ◽  
Load Capacity ◽  
Hydrodynamic Theory ◽  
Pressure Curve ◽  
Parabolic Shape ◽  
Parallel Surfaces ◽  
Gas Bearing ◽  
Theoretical Results

A hydrodynamic theory, with consideration of the effects of compressibility and inertia of the lubricant, is applied to externally pressurized gas bearings which consist of circular and parallel surfaces. The ordinary velocity distribution in a bearing clearance with a parabolic shape is changed to a velocity distribution with a shape of elliptic function due to the effect of lubricant inertia. The pressure distribution in this case differs from the ordinary pressure curve calculated without consideration of inertia, but the load capacity seems to be almost the same in both cases. The theoretical results agree in general with the experimental results reported in a previous publication [3].

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.

Analysis of Hydrodynamic Porous Bearing with External Pressure Supply

2015 ◽  
Vol 642 ◽  
pp. 328-332
Author(s):  
Dein Shaw ◽  
Hui An Hsieh ◽  
Chi Yu Lo
Keyword(s):  
Porous Material ◽  
High Speed ◽  
Load Capacity ◽  
External Pressure ◽  
Hydrodynamic Bearing ◽  
Spindle Shaft ◽  
Porous Bearing ◽  
Precision Industry ◽  
Relationship Of ◽  
The Relationship

For the need of high speed and load capacity of precision industry, a bearing used in a high speed spindle is studied. The hydrodynamic bearing composed a hydrodynamic bearing made of porous material and several hydrostatic chambers with an external oil system. The hydrodynamic bearing is pressurized with oil chamber and supports the spindle shaft both at rest and at rotation state. Because of the external pressure and the property of porous material, the load capacity of hydraulic bearing can be promoted without decreasing precision. To consider the relationship of parameters, we applied the Reynolds equation and Darcy’s law to describe the flow of the oil film between bearing and spindle shaft.

The Steady Performance of Externally Pressurized Porous Rectangular Pad Gas Bearings Incorporating Viscous and Inertia Dominated Flow

1980 ◽  
Vol 22 (4) ◽  
pp. 203-205 ◽  
Author(s):  
A. G. Naaum ◽  
G. K. Lewis
Keyword(s):  
Porous Media ◽  
Flow Rate ◽  
Effective Permeability ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
General Analysis ◽  
Three Dimensional Flow ◽  
Flow Through

A general analysis of three-dimensional flow through a porous rectangular thrust bearing which incorporates both viscous and inertia permeabilities of the porous media is presented. Solutions for load capacity and flow rate are obtained using standard numerical procedure but introducing a new term ‘the effective permeability’. It is shown that inertia flow reduces the load capacity and increases the flow rate through the bearing.

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