Christensen's stochastic theory of hydrodynamic lubrication of rough surfaces is used to study the effect of surface roughness in an infinitely long porous journal bearing operating under steady conditions. It is shown that the surface roughness considerably influences the bearing performance; the direction of the influence depends on the roughness type.

Surface Roughness Effects in Infinitely Long Porous Journal Bearings

On the basis of Christensen's stochastic model of rough surfaces, this study theoretically analyzes the effect of surface roughness on the dynamic stiffness and damping characteristics of compensated hydrostatic circular step thrust bearings. Both the stochastic Reynolds equation with rotational inertia effect and the recess flow continuity equation with recess volume fluid compressibility effect are derived to take into account the presence of roughness on the bearing surfaces. Using a small perturbation method, the dynamic coefficients of bearings are evaluated. According to the results, the mean stiffness and damping behaviours are significantly affected by the roughness pattern and the height of roughness. The effect of circumferential roughness provides an increase in the mean bearing stiffness and damping characteristics as compared to the smooth-bearing case. However, these trends are reversed for the bearing having radial roughness structure. An illustration of a design example is also included for industrial practice.

Surface roughness effect on the dynamic stiffness and damping characteristics of compensated hydrostatic thrust bearings

Forward and inverse solutions of a conductive, convective and radiative cylindrical porous fin

The effect of surface roughness on the performance of hydrodynamic slider bearings is studied. A generalized form of surface roughness characterized by a stochastic random variable with non-zero mean, variance and skewness is assumed to define the bearing surface topography. Various film shapes such as: plane slider, exponential, secant and hyperbolic are considered. The results are obtained for the general lubricant film shape in integral form which are numerically computed for the shapes under consideration. The results are presented both graphically as well as in tabular form. The performance of a rough bearing can be considered in terms of an identical smooth bearing with an equivalent film thickness. It is observed, for the lubricant film shapes under consideration, that the increasing positive values of α, σ and e decrease the load carrying capacity, frictional force and temperature rise while it increases the coefficient of friction. Increasing positive values of α and e shift the center of pressur...

Effect of Surface Roughness on Hydrodynamic Lubrication of Slider Bearings

Hydrodynamic lubrication of rough slider bearings with couple stress fluids

Lubrication of a Porous Bearing With Surface Corrugations

Roughness Effects in Porous Circular Squeeze-Plates With Arbitrary Wall Thickness

The analysis of the squeeze film between two rotating annular discs, one with a porous facing is extended to include the effect of surface roughness.A detailed study of the squeeze film characteristics for a wide range of operating parameters is made to illustrate the effect of rotation and surface roughness and their interaction.

K. Tiwari

Papers

Lubrication of a Porous Bearing With Surface Corrugations

Roughness Effects in Porous Circular Squeeze-Plates With Arbitrary Wall Thickness

Effect of Surface Roughness on the Squeeze Film between Rotating Porous Annular Discs