Showing papers on "Fluid bearing published in 1984"
Patent•
17 May 1984
TL;DR: In this article, a dynamic pressure type fluid bearing comprises a housing provided with a cylindrical hole having cylindrically shaped inner bearing surface and a bottom bearing surface for thrust load.
Abstract: A dynamic pressure type fluid bearing comprises a housing provided with a cylindrical hole having a cylindrically shaped inner bearing surface for radial load and a bottom bearing surface for thrust load, and a shaft disposed in the cylindrical hole and having a cylindrically shaped outer bearing surface for radial load opposed to and cooperative with the inner bearing surface and an end bearing surface for thrust load opposed to and cooperative with the bottom bearing surface. At least one of the inner bearing surface and the outer bearing surface is provided with grooves for generating a dynamic pressure. A communication hole is provided in the bottom bearing surface and opens to the outside of the housing. The bottom bearing surface has around the communication hole an annular contact bearing surface which contacts the end bearing surface when the bearing is stationary.
59 citations
23 citations
TL;DR: In this article, an attempt is made to study the non-isothermal flow of a power law lubricant through the gap of a conical journal bearing, where the authors assumed the width of the bearing to be infinite in order to reduce a three-dimensional problem to the two-dimensional one.
Abstract: The hydrodynamic theory of lubrication for non-Newtonian power law lubricants has been recently developed by I. Teipel et al. [1], [2], and K. Wierzcholski [3]. They restricted, however, their investigations to the cylindrical journal bearings only. Moreover, the authors assumed the width of the bearing to be infinite in order to reduce a three-dimensional problem to the two-dimensional one. In this paper an attempt is made to study the non-isothermal flow of a power law lubricant through the gap of a conical journal bearing. At first, the more general equations in curvilinear coordinates are derived which describe the flow of a power law lubricant in the bearing gap of a quite arbitrary geometry. Afterwards, as a special case, a conical bearing gap is considered. It seems to the authors that they succeeded in omitting the necessity of using numerical procedures and obtained a relatively simple, analytical solution to the problem discussed.
20 citations
Patent•
07 Feb 1984
TL;DR: In this paper, a hydrodynamic bearing is designed to work in a fluid and is formed with a central section of the load carrying surface that is more compliant so that it will deflect under load and form a pressure pocket of fluid.
Abstract: A hydrodynamic bearing is disclosed which is designed to work in a fluid. The hydrodynamic bearing is formed with a central section of the load carrying surface that is more compliant so that it will deflect under load and form a pressure pocket of fluid to carry high loads.
17 citations
TL;DR: In this article, the authors investigated the steady slow flow of an incompressible viscous fluid in the region between an inner circular cylinder rotating with constant angular velocity and an outer stationary cylinder of arbitrary cross-section.
Abstract: This paper investigates the steady slow flow of an incompressible viscous fluid in the region between an inner circular cylinder rotating with constant angular velocity and an outer stationary cylinder of arbitrary cross section The numerical solution technique known as the boundary integral equation method is employed in which the governing partial differential equations of motion are recast into coupled integral equations by repeated applications of the divergence theorem
15 citations
14 citations
TL;DR: In this paper, a numerical method of hydrodynamic bearing analysis is presented which is simple in concept, yet capable of development to handle complex situations such as dynamic misalignment, which is similar to the finite difference solution of Reynolds equation, but incorporates a more realistic modelling of cavitation.
13 citations
13 citations
04 Jun 1984
TL;DR: In this paper, direct measurements of damper forces are presented for the first time, showing that the theory of hydrodynamic lubrication is strictly valid for Reynolds numbers much less than one, which means that fluid viscous forces are much greater than inertia forces.
Abstract: Squeeze film dampers are commonly applied to high speed rotating machinery, such as aircraft engines, to reduce vibration problems. The theory of hydrodynamic lubrication has been used for the design and modeling of dampers in rotor dynamic systems despite typical modified Reynolds numbers in applications between ten and fifty. Lubrication theory is strictly valid for Reynolds numbers much less than one, which means that fluid viscous forces are much greater than inertia forces. Theoretical papers which account for fluid inertia in squeeze films have predicted large discrepancies from lubrication theory, but these results have not found wide acceptance by workers in the gas turbine industry. Recently, experimental results on the behavior of rotor dynamic systems have been reported which strongly support the existence of large fluid inertia forces. In the present paper direct measurements of damper forces are presented for the first time. Reynolds numbers up to ten are obtained at eccentricity ratios 0.2 and 0.5. Lubrication theory underpredicts the measured forces by up to a factor of two (100% error). Qualitative agreement is found with predictions of earlier improved theories which include fluid inertia forces.Copyright © 1984 by ASME
10 citations
8 citations
TL;DR: In this paper, the Navier-Stokes equations were modified by adopting the non-linear turbulence theory proposed by Constantinescu to take into account the turbulent stresses, and the modified equations were solved by the finite element method using Galerkin's technique and a suitable iterative procedure.
Patent•
16 Mar 1984
TL;DR: The bearing body for air bearings has a center of a plane bearing surface (4 ') opening the air supply port (8'). Starting from air supply opening (8 ') extend in cross section flat air guide ducts spirally in the bearing surface to the outside, so that in an air gap between the bearing surfaces (4') and a bearing counter-surface is always a pressure compensation is possible, and a tilting force is prevented on the bearing body as mentioned in this paper.
Abstract: The bearing body for air bearings has a center of a plane bearing surface (4 ') opens the air supply port (8'). Starting from the air supply opening (8 ') extend in cross section flat air guide ducts spirally in the bearing surface to the outside, so that in an air gap between the bearing surface (4') and a bearing counter-surface is always a pressure compensation is possible, and a tilting force is prevented on the bearing body. One with a suction line (15) air outlet opening (14) connected to the bearing surface (4 ') annularly surrounds, also contributes to constancy of the width of the air gap between the bearing surface (4' on) and a bearing mating surface.
TL;DR: In this article, the effect of two-sided roughness on a finite width slider bearing is investigated. But the analysis is based upon the assumption that the Reynolds equation holds in the presence of roughness and uses Christensen's stochastic models as extended to two sides roughness, and the results show that these parameters have a strong influence on the bearing behaviour.
Abstract: The paper describes the results of a numerical study concerning the effect of two-sided roughness in a finite width slider bearing. The analysis is based upon the assumption that Reynolds equation holds in the presence of roughness and uses Christensen's stochastic models as extended to two-sided roughness. Detailed results for various bearing characteristics as a function of width/length and film thickness ratio show that these parameters have a strong influence on the bearing behaviour.
01 Feb 1984
TL;DR: In this article, a simultaneous solution of both Reynolds' equation for hydrodynamic lubrication and Laplace's equation for a porous matrix, the continuity of pressure at film-bearing interface being maintained.
Abstract: This paper presents a simultaneous solution of both Reynolds' equation for hydrodynamic lubrication and Laplace's equation for a porous matrix, the continuity of pressure at film-bearing interface being maintained. Performance characteristics for an infinitely long bearing are obtained and design charts comprising optimum curves for maximum load capacity, minimum friction loss and maximum utilization of bearing bush porous material are displayed.
01 Jan 1984
TL;DR: In this paper, direct measurements of damper forces are presented for the first time and the results of lubrication theory can be greatly in error with regard to phase effects between bearing forces and displacements, which may have profound implications regarding critical speed and forced response behavior.
Abstract: : In the modeling and analysis of rotor dynamic systems, the behavior of squeeze film damper bearings is normally predicted by the Reynolds equation of hydrodynamic lubrication. Large bearing gaps and high speeds can combine to create conditions in practical applications where fluid inertia and viscoelastic effects may become significant, violating the assumptions under which Reynolds equation can be applied. The analysis shows that the results of lubrication theory can be greatly in error with regard to phase effects between bearing forces and displacements, which may have profound implications regarding critical speed and forced response behavior. Very large deviations from lubrication theory have been predicted in a series of analytical papers under this contract. In the present study direct measurements of damper forces are presented for the first time. Reynolds numbers up to ten are obtained at eccentricity ratios 0.2 and 0.5. Lubrication theory underpredicts the measured forces by up to a factor of two (100% error). Qualitative agreement is found with predictions of the improved theory which includes fluid inertia forces.
Patent•
11 Apr 1984
TL;DR: In this article, the authors proposed to use air gaps between a movable unit and a stationary unit in which a magnetic field for generating rotary motion or linear movement of the motor exists as gaps for fluid bearings.
Abstract: PURPOSE:To enhance the linearly positioning accuracy and rotating accuracy of a motor by using air gaps between a movable unit and a stationary unit in which a magnetic field for generating rotary motion or linear movement of the motor exists as gaps for fluid bearings. CONSTITUTION:A throttle 1 flows fluid flowed from an inlet 7 as compressed fluid, which is filled in a bearing gap 2. A magnetic fluid generator or a current generator 3 using magnetic material or conductor is formed on bearings 5, and a current generator or a magnetic field generator 4 using the conductor or magnetic material is provided on a shaft 6. A magnetic field for generating rotary motion or linear movement of the motor is formed between the gap 2 by the generator 3, a current is simultaneously generated by the generator 4, thereby obtaining the moving force as the motor.
TL;DR: In this article, a technique for measuring friction drag in turbulent gas and gas/particle flows over flat plates is presented, and preliminary results are reported, demonstrating good agreement with theoretical drag calculations.
Abstract: A technique for measuring friction drag in turbulent gas and gas/particle flows over flat plates is presented, and preliminary results are reported. A 0.25-in.-thick 72 x 6-in. Al plate is suspended by six horizontal support air bearings and four vertical alignment air bearings between fixed dummy plates and leading-edge and trailing-edge fairings in the 32-in.-high 48-in.-wide 11-ft-long test section of a closed-circuit atmospheric wind tunnel operating at 50-150 ft/sec. Particles of Fe and Al oxides of diameter 20-150 microns and density up to 0.3 lb particles per lb air are injected via a 6 x 0.167-in. nozzle; turbulence is induced by a roughened section of the leading-edge fairing; and friction drag is measured using a load-cell pressure transducer. Sample results are shown in a graph, demonstrating good agreement with theoretical drag calculations.