Paper 3: Recent Developments in Fluid Film Lubrication Theory

1967 ◽  
Vol 182 (1) ◽  
pp. 36-50 ◽  
Author(s):  
T. Lloyd ◽  
H. McCallion
Keyword(s):  
Finite Difference ◽  
High Speed ◽  
Lubrication Theory ◽  
Fluid Film ◽  
Special Topic ◽  
Finite Difference Schemes ◽  
Great Activity ◽  
Wide Range ◽  
Film Lubrication ◽  
Fluid Film Lubrication

Developments in high-speed electronic computers have greatly influenced the progress in fluid film lubrication over the past ten years. Static and dynamic oil film parameters have been computed for a wide range of finite geometries, for hydrostatic and hydrodynamic bearings lubricated by compressible and incompressible lubricants. These are either sufficient in themselves or else act as a yardstick against which approximate formulas may be tested. Much use has been made of iterative finite difference schemes, which are particularly well suited to digital computers, and these methods are now more fully understood. Other methods of solution include direct inversion of finite difference matrices and solution by expression of the pressure by some infinite series, a finite number of terms of which give adequate representation. Besides the increase in design data available, there has been substantial progress through a re-examination of the effects of modifying some of the assumptions inherent in most of the available solutions of the Reynolds equation. These include the assumption of constant lubricant viscosity, of rigid surfaces and of laminar flow. Major progress has been witnessed in two fields. The interaction of the lubricant film with elastic boundaries has been shown to be of prime importance in highly loaded contacts such as gears. This has led to the development of the special topic of elastohydrodynamic lubrication theory. The applicability of gas bearings in such growing industries as computers, space vehicles and nuclear reactors has resulted in great activity and progress in this field.

First Paper: Effect of Under-Lip Temperature on the Lubrication of Rotary Shaft Garter Spring Seals

1966 ◽  
Vol 181 (1) ◽  
pp. 185-190 ◽  
Author(s):  
D. J. Lines ◽  
J. M. Lawrie ◽  
J. P. O'Donoghue
Keyword(s):  
Coefficient Of Friction ◽  
Operating Temperature ◽  
Lubrication Theory ◽  
Fluid Film ◽  
Hydrodynamic Parameter ◽  
Accurate Knowledge ◽  
The Coefficient Of Friction ◽  
Surface Thermocouple ◽  
Sealing Mechanism ◽  
Film Lubrication

Although rotary shaft garter spring seals are widely used throughout industry, very little is known about the sealing mechanism of the lip-shaft interface. It is now generally accepted that some sort of fluid film separates the lip and the shaft. Previous workers have also postulated a relationship between the coefficient of friction and a non-dimensional hydrodynamic parameter, as in standard lubrication theory. This present paper clarifies this relationship, and shows that seals can also operate over the mixed friction, as well as the full film lubrication region. The results were obtained by accurate knowledge of the operating temperature under the sealing lip. Two types of surface thermocouple were developed to do this and these are described in full.

The breakdown of fluid film lubrication in elastic-isoviscous point contacts

Wear ◽  
1980 ◽  
Vol 63 (1) ◽  
pp. 25-40 ◽  
Author(s):  
J.B. Medley ◽  
A.B. Strong ◽  
R.M. Pilliar ◽  
E.W. Wong
Keyword(s):  
Fluid Film ◽  
Point Contacts ◽  
Film Lubrication ◽  
Fluid Film Lubrication

Prefactored optimized compact finite-difference schemes for second spatial derivatives

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. WB87-WB95 ◽  
Author(s):  
Hongbo Zhou ◽  
Guanquan Zhang
Keyword(s):  
Finite Difference ◽  
Difference Schemes ◽  
Compact Scheme ◽  
Finite Difference Schemes ◽  
Difference Operators ◽  
Compact Schemes ◽  
Compact Finite Difference ◽  
Wide Range ◽  
Compact Finite Difference Schemes ◽  
Spatial Derivatives

We have described systematically the processes of developing prefactored optimized compact schemes for second spatial derivatives. First, instead of emphasizing high resolution of a single monochromatic wave, we focus on improving the representation of the compact finite difference schemes over a wide range of wavenumbers. This leads to the development of the optimized compact schemes whose coefficients will be determined by Fourier analysis and the least-squares optimization in the wavenumber domain. The resulted optimized compact schemes provide the maximum resolution in spatial directions for the simulation of wave propagations. However, solving for each spatial derivative using these compact schemes requires the inversion of a band matrix. To resolve this issue, we propose a prefactorization strategy that decomposes the original optimized compact scheme into forward and backward biased schemes, which can be solved explicitly. We achieve this by ensuring a property that the real numerical wavenumbers of both the forward and backward biased stencils are the same as that of the original central compact scheme, and their imaginary numerical wavenumbers have the same values but with opposite signs. This property guarantees that the original optimized compact scheme can be completely recovered after the summation of the forward and backward finite difference operators. These prefactored optimized compact schemes have smaller stencil sizes than even those of the original compact schemes, and hence, they can take full advantage of the computer caches without sacrificing their resolving power. Comparisons were made throughout with other well-known schemes.

scholarly journals Mixed and Fluid Film Lubrication Characteristics of Worn Journal Bearings

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Toshiharu Kazama ◽  
Yukihito Narita
Keyword(s):  
Frictional Coefficient ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Fluid Film ◽  
Asperity Contact ◽  
Lubrication Regimes ◽  
Lubrication Characteristics ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The mixed and fluid film lubrication characteristics of plain journal bearings with shape changed by wear are numerically examined. A mixed lubrication model that employs both of the asperity-contact mechanism proposed by Greenwood and Williamson and the average flow model proposed by Patir and Cheng includes the effects of adsorbed film and elastic deformation is applied. Considering roughness interaction, the effects of the dent depth and operating conditions on the loci of the journal center, the asperity-contact and hydrodynamic fluid pressures, friction, and leakage are discussed. The following conclusions are drawn. In the mixed lubrication regime, the dent of the bearing noticeably influences the contact and fluid pressures. For smaller dents, the contact pressure and frictional coefficient reduce. In mixed and fluid film lubrication regimes, the pressure and coefficient increase for larger dents. Furthermore, as the dent increases and the Sommerfeld number decreases, the flow rate continuously increases.

Optimum Design of Hydrostatic Spherical Bearings in Fluid Film Lubrication

2000 ◽  
Vol 122 (4) ◽  
pp. 866-869 ◽  
Author(s):  
Toshiharu Kazama
Keyword(s):  
Optimum Design ◽  
Analytical Solutions ◽  
Power Loss ◽  
Fluid Film ◽  
Optimal Size ◽  
Minimum Power ◽  
Maximum Stiffness ◽  
The Difference ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The optimum design of hydrostatic spherical bearings in fluid film lubrication is examined theoretically. The analytical solutions are derived for both fitted and clearance types of bearings with capillary and orifice restrictors. The optimal size based on the minimum power loss and the maximum stiffness is presented, and the difference between two types of bearings is discussed. [S0742-4787(00)02204-9]

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