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Showing papers on "Fluid bearing published in 1986"


Journal ArticleDOI
TL;DR: In this article, a conceptual and experimental investigation of the mechanism of mixing in the groove, in terms of the relevant flows and temperatures, is presented, and empirical equations based on the above correlation for the determination of the inlet temperatures are then given for both thrust and journal bearings.
Abstract: Cold and hot lubricant mixing at the inlet to a hydrodynamic bearing has been an unresolved and critical problem in determining bearing performance. The paper offers a conceptual and experimental investigation of the mechanism of mixing in the groove, in terms of the relevant flows and temperatures. The carryover from pad to pad of the discharging hot fluid film, the flow dynamics in the groove and the effects of cavitation are all determined in detail in the light of available experiments. Results of an extensive series of tests aimed at measuring the mixing inlet temperatures as a function of a range of operating conditions and bearing sizes are correlated in terms of an appropriate mixing function. Empirical equations based on the above correlation for the determination of the inlet temperatures are then given for both thrust and journal bearings.

90 citations


Journal ArticleDOI
TL;DR: In this article, a power-law, non-Newtonian lubricant was used for bearing aspect ratios in the range 0.1 to 0.6 and clearance ratios of 1.2 to 4.0.
Abstract: The lubrication of a conventional, finite width plane bearing, using a power-law, non-Newtonian lubricant, is studied. The basic assumptions in this analysis are: thin fluid-film, no thermal effects, and a modified Reynolds' equation for small bearing aspect ratios. Results from this study include bearing pressure, load, and friction formulas. Similar results for the not-so-small bearing aspect ratios are found via an Euler-Lagrange equation. This Euler-Lagrange equation is derived from the optimization integral for the modified Reynolds' equation. Approximate solutions to the modified Reynolds' equation and to the Euler-Lagrange equation are contrasted with numerical solutions for the modified Reynolds equation. Bearing aspect ratios in the range 0.1 to 0.6, clearance ratios in the range 1.2 to 4.0, and non-Newtonian power-law index in the range 0.4 to 1.0 are considered.

41 citations


Patent
08 Jul 1986
TL;DR: In this paper, a dynamic pressure fluid bearing is used to ensure a minute gap between the shaft of a bearing and a bearing, where fluid intervenes between the bearing and the shaft and these two rotate relative to each other in a noncontact state.
Abstract: A dynamic pressure fluid bearing, and particularly a dynamic pressure fluid bearing for effectively ensuring a minute gap between the shaft of the dynamic pressure fluid bearing and a bearing. More particularly, fluid intervenes between the shaft and the bearing and these two rotate relative to each other in a non-contact state, and a part or the whole of the bearing is formed of resin and the resin is endowed with electrical conductivity.

32 citations


Journal ArticleDOI
TL;DR: In this paper, the linearized bearing coefficients for oil lubricated plain line-entry (slot) hybrid journal bearings are presented and compared using finite disturbance and perturbation techniques.

29 citations


Patent
05 May 1986
TL;DR: In this article, a pressure-responsive system for controlling the flow of magnetic fluid to and from a bearing or seal is presented. But the system is not suitable for magnetic bearing or fluid seal.
Abstract: Provides new magnetic fluid bearings and magnetic fluid seals incorporating a pressure responsive system for automatically controlling the supply of magnetic fluid to the magnetic fluid feed area of such bearing or seal. The system for controlling the supply of magnetic fluid includes a reservoir of magnetic fluid and a conduit leading from the reservoir to the magnetic fluid feed area of the magnetic fluid bearing or magnetic fluid seal. A portion of the conduit is subjected to a magnetic field which establishes a pressure responsive magnetic fluid plug in that portion of the conduit to automatically control the flow of magnetic fluid to and from the reservoir as a function of the difference in pressure between the magnetic fluid feed area of the bearing or seal and the reservoir.

23 citations


Journal ArticleDOI
TL;DR: In this article, the authors extend the Reynolds equation to include the inertia effects in hydrodynamic lubrication and obtain explicitly the inertia contributions to the dynamics of bearings in some particular cases.

20 citations


Journal ArticleDOI
TL;DR: In this article, the particular problem of a misaligned journal bearing has been studied by solving simultaneously the Reynolds and energy equations, which also include the effects of viscous dissipation and the variation of fluid viscosity with temperature.
Abstract: The analysis presented herein deals with the evaluation of pressure and temperature fields which are generated in thin fluid films of varying thickness. The particular problem of a misaligned journal bearing has been studied by solving simultaneously the Reynolds and energy equations, which also include the effects of viscous dissipation and the variation of fluid viscosity with temperature. The method has been used to predict pressure and temperature fields as well as global performance parameters for a typical journal bearing operation.

17 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented an analytical study of dynamic characteristics of half-elliptical pressure dam bearings, where one half (either upper or lower) of these bearings is elliptical, while the other half is circular.
Abstract: This paper presents an analytical study of dynamic characteristics of half-elliptical pressure dam bearings. One half (either upper or lower) of these bearings is elliptical, while the other half is circular. A step or pressure dam is cut in the upper half bearing surface. The lower half bearing surface is provided with a deep groove or relief-track. These bearings have been analyzed by the finite-element method. The results have been computed for dimensionless rotor flexibilities of 0.0, 0.5, 1.0, 2.0, and 4.0. Dynamic characteristics such as stiffness and damping coefficients, and stability threshold speed are presented in the form of graphs. It has been determined that half-elliptical pressure dam bearings are superior to circular pressure dam bearings in stability for bearings having same design parameters. Both these half-elliptical pressure dam bearings have almost identical dynamic characteristics. Rotor flexibility adversely affects the stability of these bearings and its effect is pronounced at h...

15 citations



Journal ArticleDOI
TL;DR: In this article, a theoretical investigation is made to study the way in which thermal distortion of bearing components modifies the characteristics of journal bearings, and the effect of thermal distortion is to reduce the minimum film thickness, increase the load capacity, increase peak temperatures and pressures, and also to enhance considerably the stability of the bearing.
Abstract: A theoretical investigation is made to study the way in which thermal distortion of bearing components modifies the characteristics of journal bearings. The thermoelastic treatment developed is two-dimensional and incorporates an existing thermohydrodynamic analysis. It is applied to circular and partial arc bearings for a range of parametric groups governing the bearing operation. The results show that for a fixed journal position, the effect of thermal distortion is to reduce the minimum film thickness, increase the load capacity, increase the peak temperatures and pressures, and also to enhance considerably the stability of the bearing. The effects are more marked for larger oil-lubricated bearings and higher speeds of operation and it is suggested that discrepancies observed between experimental results and existing theory could be largely explained by this phenomenon.

12 citations


Journal ArticleDOI
TL;DR: In this paper, wide thrust bearings operating in laminar inertial flow regimes are studied. Integro-differential equations of motion, continuity and energy equations are solved to yield pressure, mass-mean velocity and temperature distributions.

Journal ArticleDOI
TL;DR: In this paper, the axial grooves between the pockets and either one or two pockets per pad are calculated for bearing properties, and the resulting turbulent flow can be analyzed by considering three major pressure drops.
Abstract: Hydrostatic journal bearings have been employed in several applications where the lubricant is a working fluid with low viscosity. The resulting turbulent flow can be analyzed by considering three major pressure drops: pressure drop across the orifice restrictor, pressure drop over the pocket edges, and pressure drop across the bearing lands. This paper presents a finite element analysis of bearings in the above category. The bearings here have axial grooves between the pockets and either one or two pockets per pad. Both static and dynamic bearing properties are calculated for example bearings. Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

01 Jan 1986
TL;DR: In this article, a simulation model based on the theory of lubrication including inertial effects was developed to determine the periodical variations of the distribution of clearances in a single screw compressor.
Abstract: The hydrodynamic lubrication of the teeth of the gaterotor in a single screw compressor differs from the well-known lubrication of bearings. This difference can be related to the constrained fluid film geometry and the conditions of the lubrication. Under these circumstances the convective fluid inertia will affect the performance of the lubrication. During meshing, variations of the filmgeometry and the conditions of lubrication result in variations of the distribution of the clearances. A simulation model, based on the theory of lubrication including inertial effects, has been developed to determine the periodical variations of the distribution of clearances. Changes in design can be studied and parametric analyses can be made with this model, resulting in an optimum design.

Journal ArticleDOI
TL;DR: In this paper, a solution analytique for la lubrification hydrodynamique d'un palier de longueur finie a surface rugueuse is presented.
Abstract: Solution analytique pour la lubrification hydrodynamique d'un palier de longueur finie a surface rugueuse


Patent
15 Mar 1986
TL;DR: In this article, the starting torque of a bearing can be reduced by mixing a small amount of molybdenum disulfide with silicone oil as a base oil, and a limit exists in the viscosity of the lubricant which can flow into the minute gap in the radial direction of bearing as a dynamic pressure bearing.
Abstract: PURPOSE:To reduce the starting torque and obtain the stable performance over a wide temperature range by using the lubricant which consists of grease having a consistency No.1 or less mixed with molybdenum disulfide, added with silicone oil as base oil. CONSTITUTION:The grease which contains silicone oil as base oil has the most stable viscosity as the lubricant for bearing, and a limit exists in the viscosity of the lubricant which can flow into the minute gap in the radial direction of bearing as a dynamic-pressure bearing, and only the lubricant having the viscosity of consistency No.1 or less flows into the gap sufficiently. Further, the annular contact surface 71 of a shaft body 1 and the thrust bearing surface 41 of a thrust bearing member contact with high contact-surface pressure on stop or low-speed revolution of the bearing, and though the starting torque tends to become excessively large, the starting friction of the bearing can be markedly improved by mixing a small amount of molybdenum disulfide.

Journal ArticleDOI
TL;DR: In this paper, the necessary conditions for backward motion of a Jeffcott rotor supported by identical hydrodynamic journal bearings are investigated, and it is shown that backward motion occurs if and only if the load parameter is greater than a limiting value corresponding to the flexibility parameter.

Journal ArticleDOI
TL;DR: In this article, a linearization method was presented to study the effect of fluid inertia in fluid film bearings, and the results were obtained in closed form which were previously amenable only to numerical analysis or asymptotic analysis.

Patent
31 Mar 1986
TL;DR: In this article, a fluid bearing assembly includes a first element and a second element which moves relative to the first element along a predetermined path, and a recess is defined at least in either one of the first or second surfaces for maintaining a quantity of fluid.
Abstract: A fluid bearing assembly includes a first element and a second element which moves relative to the first element along a predetermined path. The first element has a first surface which is opposite to a second surface of the second element. A recess is defined at least in either one of the first or second surfaces for maintaining therein a quantity of fluid, such as air and liquid. Also provided is a heater inside of the recess so that the fluid inside of the recess is heated to expand in volume, thereby pressurizing the fluid to establish alignment between the first and second elements. Such a fluid bearing assembly may be applied not only for the rotary type bearing assembly, but also for the linear motion type bearing assembly.


Journal ArticleDOI
TL;DR: In this article, a theoretical analysis for the stability characteristics of an unloaded rigid rotor supported in hydrodynamic porous oil journal bearings with tangential velocity slip on the bearing film interface is presented.

Journal ArticleDOI
15 Feb 1986-Wear
TL;DR: In this article, the analysis of tapered land aerostatic Yates' bearings for supporting combined radial and thrust loads is presented, where air flow in the journal and thrust bearings is expressed in terms of the Reynolds equation and the Navier-Stokes equations respectively.


Patent
31 Jul 1986
TL;DR: In this paper, the authors proposed to improve the load-resistivity at the time when the fluid groove is pressed by a hard metallic die, and to obtain a bearing which scarcely causes a residual strain and has high fluid groove working accuracy, by allowing a soft metallic thin film to contact to the surface of a hard metal by vapor-deposition or spattering.
Abstract: PURPOSE: To improve the load-resistivity at the time when the fluid groove is pressed by a hard metallic die, and to obtain a bearing which scarcely causes a residual strain and has high fluid groove working accuracy, by allowing a soft metallic thin film to contact to the surface of a hard metal by vapor- deposition or spattering. CONSTITUTION: When a driving motor 1 rotates, the thrust works on a feed screw 3 through a speed reducer 2, and the surface of a soft metallic material 6 which has formed a thin film on the surface of a hard metal 7 by vapor- deposition or spattering is pressed by a hard metallic die 5 attached to a ram 4, by which a fluid groove is formed. By allowing a copper alloy thin film 6 to contact with the surface of the hard metal 7, the load-resistivity at the time when the fluid groove is pressed by the hard metallic die 5 is improved, and also, by forming a soft metallic material which can be brought to plastic working easily, to a thin film, the fluid groove which scarcely causes a residual strain and has high working accuracy is obtained. COPYRIGHT: (C)1988,JPO&Japio

Journal ArticleDOI
TL;DR: In this paper, a better knowledge of several critical parameters might improve the load capacity of squeeze film air bearings and discuss the applicability of some methods of analysis for practical applications, and the aim is to define some of these critical parameters and discuss their applicability.

Journal ArticleDOI
15 Nov 1986-Wear
TL;DR: In this article, a series of experiments were described and analyzed where the frictional characteristics of two reciprocating fluid-lubricated polymeric bushes were tested under conditions characteristic of hydraulic strut bearings.

Journal ArticleDOI
01 Apr 1986-Wear
TL;DR: In this paper, the stiffness and damping characteristics of a finite hydrodynamic journal bearing using the new boundary conditions are compared with the wellknown characteristics incorporating the Reynolds boundary conditions.

Journal ArticleDOI
TL;DR: In this paper, a modified Darcy's law for a Bingham solid postulated by the author to porous journal bearings lubricated with grease is applied to analyze how the yield stress and the permeability coefficient of a porous matrix affect the flows of lubricating film and porous metal.
Abstract: Porous materials find a wide range of applications as bearing metals because of their self-lubricating action. On the other hand, grease its widely used as a lubricant for porous metal bearings because of its simplicity of application. Unfortunately, since the governing law for flows of grease in porous matrices, that is Equivalent to Darcy's law for Newtonian fluids, has not been established, the hydrodynamic lubrication of porous metal bearings with grease has not been reported. Applying a modified Darcy's law for a Bingham solid postulated by the author to porous journal bearings lubricated with grease, this paper analyzes how the yield stress of a Bingham solid and the permeability coefficient of porous matrix affect the flows of lubricating film and porous metal.