Lubrication Of Journal Bearings Research Articles

Axial Laminar Flow of Non-Newtonian Fluids in Narrow Eccentric Annuli

Abstract The analysis of laminar flow of power-law non- Newtonian fluids in narrow, eccentric annuli is employed in this paper to discuss the problems of lubricant flow in journal bearings and of errors introduced by eccentricity in experimental studies with concentric annuli on extruders and wellbore annuli. The velocity profile and pressure loss-flow rate equations are developed for the laminar flow region. In addition, the expected error in flow rate and pressure-loss measurements for concentric annuli as a result of eccentricity is determined. For example, a 10 per cent displacement of the core of an almost concentric annulus would cause a 1.8 per cent decrease in the observed pressure loss for a fluid with a power-law exponent n of 0.25. The corresponding increase in the observed volumetric flow rate would be 7.5 per cent. Introduction Non-Newtonianism and eccentricity occur simultaneously in two engineering problems: flow of lubricants in journal-bearings and pressure-reducing bushings, and flow of non-Newtonian fluids in plastic extruders and wellbore annuli. The lubricants used for moving parts are often non-Newtonian in character - often they are plastic in behavior. A solution to the problem of flow of non-Newtonian fluids in narrow eccentric annuli is particularly pertinent to this problem. In all experimental studies of laminar flow of fluids in concentric annuli, such as in extruders and well casings, the error due to eccentricity must be estimated or studied. A number of publications have dealt with this problem for Newtonian fluids; however, I am not aware of work for non-Newtonian fluids. This work is directed to the non-Newtonian problem. Before the solution to the problem is given, the pertinent conclusions from the work on Newtonian fluids will be reviewed. Heyda and Redberger and Charles have published general solutions to the problem of the laminar flow of Newtonian fluids in eccentric annuli, apparently without knowing of the earlier work of Caldwell and Bairstow and Berry, which is reported by Dryden, et al. Although several mathematical routes are encompassed by the work of these authors, the results appear to be equivalent. Redberger and Charles show that the error caused by eccentricity in concentric annuli is negligible for small diameter ratios (K less than 0.5); however, for large diameter ratios (K - 1), the error in the predicted flow rate can be as great as 100 per cent or more. Partial solutions to the problem are available from the work of Dryden, Tao and Donovan and Piercy, et al. Tao and Donovan examined the case of flow in narrow, eccentric annuli (K - 1) with and without rotation of the annular core. These authors also reviewed previous work on this subject and verified their approach with experimental data. Dryden gives the solution for the limiting case of complete eccentricity or tangency. Piercy, et al. published an early solution to the problem of narrow eccentric annular flow. The conclusions of Redberger and Charles and the experimental proof of Tao and Donovans both suggest that the region of large diameter ratios (K - 1) is of main interest and that the parallel planes approximation to the solution in this region is satisfactory. This method will now be extended to the laminar flow of non-Newtonian fluids in narrow eccentric annuli. THEORETICAL SOLUTION The geometrical aspects of the problem are illustrated in Fig. 1. To represent the non-Newtonian fluid the power-law model was selected. (1) This model has many disadvantages which have been pointed out; nevertheless, As simplicity, its frequent and wide applicability justify its use in this work. Fredrickson and Birds and Savins have used it as a basis for a theoretical study of laminar flow of non-Newtonian fluids in concentric annuli. SPEJ P. 277ˆ

The Short Gas Lubricated Journal Bearing

Technical Briefs The Short Gas Lubricated Journal Bearing H. J. Sneck H. J. Sneck Advanced Technology Laboratories, General Electric Company, Schenectady, N. Y. Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information H. J. Sneck Advanced Technology Laboratories, General Electric Company, Schenectady, N. Y. J. Basic Eng. Dec 1965, 87(4): 1087-1089 (3 pages) https://doi.org/10.1115/1.3650817 Published Online: December 1, 1965 Article history Received: April 5, 1965 Online: November 3, 2011

Note on Numerical Solutions for Gas Lubricated Journal Bearings

Note on Numerical Solutions for Gas Lubricated Journal Bearings

Calculated performance of non-newtonian lubricants in finite width journal bearings : H. H. Horowitz and F. E. Steidler. ASLETrans., 4 (1961) 275–281

Calculated performance of non-newtonian lubricants in finite width journal bearings : H. H. Horowitz and F. E. Steidler. ASLETrans., 4 (1961) 275–281

Analytical and Experimental Study of Externally Pressurized Air Lubricated Journal Bearings

A simplified analysis for calculating the characteristics, such as stiffness, flow, and load of an externally pressurized gas journal bearing, is obtained through a standard one-dimensional flow approach altered to take into account the effect of circumferential pressure variations. From this analysis, it is revealed that bearing stiffness has an optimum which, it is further shown, can be chosen through a proper selection of bearing design parameters, such as radial clearance, upstream resistor, and supply pressure. As the analysis is developed each assumption is experimentally verified. The final predictions of the analysis are also verified. It is felt that the analysis is sufficiently simple to allow comparison of many different bearing configurations, while sufficiently complete to compare very well against experimental measurements in all respects. A comparison is made between the recessed and nonrecessed bearing.

Calculated Performance of Non-Newtonian Lubricants in Finite Width Journal Bearings

A numerical procedure has been developed for the calculation of the performance of non-Newtonian, polymer-thickened lubricants in finite width journal bearings. Such oils were found to act as if they had averaged “anisotropic viscosities,” i.e., different viscosities in the circumferential and side leakage directions, even though the viscosity was taken to have one definite value, a function of the resultant shear stress, at each point in the oil film. Overall, polymer oils carried less load at a given eccentricity, gave less friction and a flatter pressure distribution than mineral oils of the same low shear viscosities. By analogy with the previously calculated infinite width case, which gave similar results, it is expected that the flatter viscosity temperature slope of the polymer oils will compensate for their apparent viscosity decrease. The program has also been adapted to “natural” boundary conditions, which improve upon the delineation of the cavitation region on the inlet side of the bearing. Co...

Investigation of oil additives for boundary lubrication of railroad journal bearings : Arnold Miller and Arthur A. Anderson. ASLE Translations, v. 1, no. 2, Oct. 1958, p. 273–280

Following a failed course of conservative management, arthroscopic rotator cuff repair (ARCR) has become the gold standard treatment for patients presenting with symptomatic rotator cuff (RC) tears. Traditionally, the single-row repair technique was used. Although most patients enjoy good to excellent clinical outcomes, structural healing to bone remains problematic. As a result, orthopaedic surgeons have sought to improve outcomes with various technological and technical advancements. One such possible advancement is the double-row technique.We present a method for repairing an RC tear using double-row suture anchors in a transosseous equivalent suture bridge technique. The double-row technique is believed to more effectively re-create the anatomic footprint of the tendon, as well as increase tendon to bone surface area, and apposition for healing. However, it requires longer operating times and is costlier. This report highlights this technique for ARCR in an adult by using a double-row transosseous equivalent suture bridge.

A theory of lubrication in journal bearings with an elastically bent shaft

A theory of lubrication in journal bearings with an elastically bent shaft

A theory of lubrication in short journal bearings with turbulent flow : I. N. Tao ASME, Transactions, v. 80, no. 8, Nov. 1958, p. 1734–1740

A theory of lubrication in short journal bearings with turbulent flow : I. N. Tao ASME, Transactions, v. 80, no. 8, Nov. 1958, p. 1734–1740

Closure to “Discussions of ‘A Theory of Lubrication in Short Journal Bearings With Turbulent Flow’” (1958, Trans. ASME, 80, pp. 1738–1739)

Closure to “Discussions of ‘A Theory of Lubrication in Short Journal Bearings With Turbulent Flow’” (1958, Trans. ASME, 80, pp. 1738–1739)

The effect of lubricant inertia in journal-bearing lubrication : J. F. Osterle, Y. T. Chou, and E. A. Saibel. Journal of Applied Mechanics, v. 24, Dec. 1957. P. 494–496

The effect of lubricant inertia in journal-bearing lubrication : J. F. Osterle, Y. T. Chou, and E. A. Saibel. Journal of Applied Mechanics, v. 24, Dec. 1957. P. 494–496

The Effect of Lubricant Inertia in Journal-Bearing Lubrication

Abstract The Reynolds equation of hydrodynamic theory, modified to take lubricant inertia into approximate account, is applied to the steady-state operation of journal bearings to determine the effect of lubricant inertia on the pressure developed in the lubricant. A simple relationship results, relating this “inertial” pressure to the Reynolds number of the flow. It is found that the inertia effect can be significant in the laminar regime.

Testing Characteristics of Bearing Metals

A comprehensive scheme of lubrication now being carried out for the British Ship building Research Association by the Royal Technical College, Glasgow, in their Department of Civil and Mechanical Engineering has included work on journal bearings, and a paper entitled “Some Factors in the Design and Lubrication of Journal Bearings” by Prof. A. S. T. Thomson, D.Sc., Ph.D., Prof. A. W. Scott, B.Sc., Ph.D., W. Ferguson, B.Sc., and H. L. McBroom, B.Sc., Ph.D. was recently read before the Institution of Engineers and Shipbuilders in Scotland, and this gave details of this work. We give here a shortened version of this paper.

Measurements of Combined Frictional and Thermal Behavior in Journal-Bearing Lubrication

Abstract Data were obtained in tests with a four-bearing friction machine which show that an increase in the load on a journal bearing produces a proportional increase in frictional torque when other conditions of test are held constant. Under these same conditions an increase in load also produces a proportional increase in the fluidity of the oil in the bearing. These two effects are the result of the combined hydrodynamic and thermodynamic actions involved in journal-bearing operation with forced-feed lubrication. The increase in torque is influenced by the viscosity of the oil, the oil-inlet temperature, the oil-feed pressure, the shaft diameter, the clearance-diameter ratio, and the length-diameter ratio. The increase in fluidity is influenced by the same factors and also by the speed of the journal. Empirical equations are derived for the fluidity-pressure relationship for certain conditions. Also, a graphical method is given for the use of this relationship in estimating safe bearing loads.

The Thick-Film Lubrication of Full Journal Bearings of Finite Width

Abstract A discussion is given of the results of analytical and experimental studies of the thick-film lubrication of full journal bearings of finite width. The Reynolds differential equation has been solved by a successive approximation method for (a) flooded full journal bearings, (b) full journal bearings with central circumferential grooves, and (c) full journal bearings provided with point sources of lubricant. Calculations were made on the variation of the journal eccentricity, load-carrying capacity, and friction coefficients with the Sommerfeld dimensionless variable for the three cases and for different bearing widths. Direct experimental tests are described which confirmed the theoretical predictions for bearings fed with lubricant at point sources.

Studies in Lubrication. III. The Theory of the Thick Film Lubrication of a Complete Journal Bearing of Finite Length with Arbitrary Positions of the Lubricant Source

A successive approximation theory is developed for the thick film lubrication of complete journal bearings of finite length for arbitrary positions of the lubricant source. It has been carried through in detail up to the third approximation, which permits studies of systems having journal eccentricities up to the value of ½. The range of bearing length for which the theory is valid includes such as are of the order of, or greater than, half the bearing perimeter. Detailed calculations are reported on the inter-relationships between the attitude of the line of centers of the journal and bearing, the journal eccentricity, the lubricant source strength, the ``Sommerfeld variable,'' (r2/c2)μN/P—where r=journal radius, c=radial clearance, μ=lubricant viscosity, N=journal speed and P=bearing load per unit projected bearing area—and the coefficient of friction, both for lubricant sources set at the crown and base of the bearing. Most of the numerical results refer to the case where the bearing length equals the bearing perimeter. In general it is found that when the lubricant source is at the crown or unloaded portion of the bearing, it tends to increase the journal eccentricities, oppose the journal supporting forces caused by the journal rotation, and increase the friction coefficients. When the source is set at the base, or loaded side, of the bearing, and has a strength less than the ``critical value,'' determined by the bearing length, it tends to decrease the journal eccentricities, to aid in supporting the load, and to decrease the friction coefficients on the journal. At the ``critical values'' of source strength the journal becomes concentric with the bearing and the lubricant source alone supports the load. For higher values of source strength the journal is raised above the center of the bearing so that the journal rotation detracts from the load-carrying power of the film, and the friction coefficient on the journal begins to rise. Moreover, when the source is set at the base of the bearing, the friction coefficient curves for both the bearing and journal, when plotted against the Sommerfeld variable, all go through the origin in contrast to the infinitely long bearing theory where the coefficient of friction on the journal has a unit friction axis intercept. From the hydrodynamic point of view there are therefore no minima in the curves, or suggestions of thin film friction rises when the lubricant source is at the base of the bearing.

Effects of Side Leakage in 120-Degree Centrally Supported Journal Bearings

Abstract Theoretical treatment of journal-bearing lubrication, based on the assumption that the bearing is infinitely wide, and hence has no oil flow from the sides of the film, has been brought to a high degree of development during recent years. Less is known, however, of the various phenomena that occur in an actual oil film. Experiments, necessarily on a bearing of finite proportions and from which oil is leaking at the sides of the film, show results entirely different from those predicted by the theory which takes no account of side leakage. From the viewpoint of bearing design, it is highly desirable to have further information for applying the excellent theoretical charts now available. The most important work on this problem has been done by A. G. M. Michell (4) and Albert Kingsbury (5). In 1905, Mr. Michell published a mathematical solution for a plane slide block of finite width. In all cases considered, he assumed the film thickness at the entering edge to be twice that at the trailing edge. The oil viscosity was assumed constant throughout the film. In 1931, Mr. Kingsbury published a method of investigating any film form regardless of shape, viscosity variation, or boundary conditions. In a later publication (6), Mr. Kingsbury introduced the idea of optimum bearing conditions and pointed out that in the case of a plane rectangular slide block the best results at finite and infinite widths are not found with the same film form. By means of the method developed and used by Mr. Kingsbury, the present paper undertakes an analysis of this problem in the case of 120-deg centrally supported journal bearings. The effect of side leakage is found to vary not only with the bearing dimensions of length and width, but also with the load carried by a bearing of given proportions. Results are given in tabular form and also by curves, and from these, optimum operating conditions are apparent. The problem of the best bearing for a given minimum film thickness, load, speed, and journal diameter is treated, the only assumption being a desired average oil viscosity in the film.

Some Problems in the Lubrication of Vertical Journal Bearings

Abstract In deep-well pumping a motor at the surface drives a pump runner at the water level through a long vertical shaft supported at the top by a thrust bearing and guided at intervals of its length by journal bearings. For effective design the power absorbed by the journal bearings should be known approximately. The preponderance of horizontal shafts in various kinds of machinery has resulted in an extensive literature on their lubrication, but there is little that bears on the lubrication of such vertical shafts as are used in pumps, hydraulic turbines, a few steam turbines, cream separators, and centrifuges. The friction loss in these is small, but in the deep-well pump the loss may be as great as 5 per cent of the power input. The paper relates the details of an investigation to establish some of the basic facts underlying the lubrication of vertical journal bearings such as are used in deep-well pumps.

Discussion: “On the Laws of Lubrication of Journal Bearings” (Hersey, M. D., 1915, Trans. ASME, 37, pp. 167–199)

Discussion: “On the Laws of Lubrication of Journal Bearings” (Hersey, M. D., 1915, Trans. ASME, 37, pp. 167–199)