On the Load Capacity of the MHD Journal Bearing

1968 ◽  
Vol 90 (1) ◽  
pp. 139-144 ◽  
Author(s):  
S. J. Dudzinsky ◽  
F. J. Young ◽  
W. F. Hughes
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Journal Bearing ◽  
Hartmann Number ◽  
Load Capacity ◽  
External Source ◽  
Diameter Ratio ◽  
Experimental Results ◽  
Eccentricity Ratio ◽  
Applied Current

An analysis and experimental results are presented for a magnetohydrodynamic partial journal bearing using a liquid metal lubricant. An external magnetic field is applied axially along the journal, and current is permitted to flow between the journal and bearing. The analysis shows that increased load capacity can be achieved by supplying current from an external source. In addition, the analysis reveals the existence of an optimum Hartmann number at which the load capacity peaks for a given applied current. This optimum value is about 5 for a dimensionless current I¯ = −5 applied to a bearing with a width/diameter ratio of 1 and an eccentricity ratio of 0.6. Experimental results which demonstrate the increase in load capacity resulting from an externally applied current are presented graphically and compared with the theory.

The Characteristics of a Statically Loaded Journal Bearing with Superlaminar Flow

1980 ◽  
Vol 22 (2) ◽  
pp. 79-94 ◽  
Author(s):  
R. E. Hinton ◽  
J. B. Roberts
Keyword(s):  
Friction Factor ◽  
Journal Bearing ◽  
Load Capacity ◽  
Reynolds Numbers ◽  
Diameter Ratio ◽  
Experimental Results ◽  
Empirical Theory ◽  
Clearance Ratio ◽  
Friction Factors ◽  
Theoretical Predictions

Experimental results are presented, relating to the friction factor, load capacity and attitude angle, for a plain, cylindrical journal bearing with a central, circumferential inlet groove. The length to diameter ratio of the journal bearing was 1/3 and the clearance ratio was 0.011. By the use of various lubricants, including water, Reynolds numbers ranging from 40 to 50 000 were attained. Comparisons with various theoretical predictions are given. It is shown that a simple, empirical theory, which incorporates measured friction factors, gives better agreement with the experimental load capacity results than previous theories.

Analysis of Fluid Film Lubrication of an MHD Journal Bearing Subjected to an Axially Applied External Magnetic Field

2013 ◽  
Vol 437 ◽  
pp. 136-139 ◽  
Author(s):  
Chin Lung Chang ◽  
Yu Min Li ◽  
Hsing Hui Huang ◽  
Jik Chang Leong
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Journal Bearing ◽  
Axial Direction ◽  
Eccentricity Ratio ◽  
Steady State Flow ◽  
Bearing Current ◽  
Applied External Magnetic Field ◽  
Film Lubrication ◽  
Fluid Film Lubrication

This work simulates the steady-state flow field in a magnetohydrodynamic journal bearing. A uniform magnetic field is applied in the axial direction across the bearing. Current results indicate that a crescent-shape secondary flow will develop at E = 0.8. The velocity profiles at the location of the minimum and maximum film thickness are almost independent of the strength of the external magnetic field unless the eccentricity ratio is relatively small and magnetic field is strong. There exists an eccentric dependent threshold Ha beyond which the shear stress on the journal increases with Ha while that on the bearing decreases.

Surface Roughness and Magnetic Effect of Magnetized Journal Bearings Lubricated with Ferrofluid

2015 ◽  
Vol 642 ◽  
pp. 242-247
Author(s):  
Tze Chi Hsu ◽  
Jing Hong Chen ◽  
Tsu Liang Chou ◽  
Hsiu Lu Chiang
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Load Capacity ◽  
Hydrodynamic Pressure ◽  
Critical Value ◽  
Journal Bearings ◽  
Diameter Ratio ◽  
Eccentricity Ratio ◽  
High Eccentricity ◽  
The Magnetic Field

This study investigated the combined influence of stochastic surface roughness patterns and a magnetic field produced by an infinitely long wire on the distribution of hydrodynamic pressure in journal bearings lubricated with ferrofluids. According to our results, the magnetic field can raise the dimensionless pressure, improve the dimensionless load capacity and reduce the modified friction coefficient, especially at high eccentricity ratio. However, these bearing Characteristics are also influenced by surface roughness pattern depend on the length to diameter ratio λ, and the critical value of λ equal to 0.6, 0.95 and 1.8 in this study.

The mmW Band Tamm States in One-Dimensional Magnetophotonic Crystals

2009 ◽  
Vol 152-153 ◽  
pp. 394-396 ◽  
Author(s):  
Sergey I. Tarapov ◽  
M. Khodzitskiy ◽  
S.V. Chernovtsev ◽  
D. Belosorov ◽  
A.M. Merzlikin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Theoretical Prediction ◽  
Experimental Results ◽  
One Dimensional ◽  
Magnetophotonic Crystals ◽  
Good Agreement

The mmW band photonic Tamm states in 1D magnetophotonic crystals are studied. It is shown the possibility to manipulate the eigenfrequencies of such states by an external magnetic field. Our experimental results are in a good agreement with theoretical prediction.

Magnetization and Curie Temperature of Ferromagnetic Ultrathin Films: The Influence of Magnetic Anisotropy and Dipolar Interactions (invited)

1991 ◽  
Vol 231 ◽  
Author(s):  
P. Bruno
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Curie Temperature ◽  
Magnetic Anisotropy ◽  
Long Range ◽  
Ultrathin Films ◽  
Experimental Results ◽  
Dipolar Interactions ◽  
Surface Gradient ◽  
Theoretical Investigations

AbstractTheoretical investigations of the magnetization and Curie temperature of ferromagnetic ultrathin films in the presence of magnetic anisotropy and long-range dipolar interactions are presented. The Curie temperature of fcc (001) cobalt ultrathin films is calculated and compared with experimental results on Co/Cu (001) films. The influence of an external magnetic field, and the surface gradient of the magnetization are also discussed.

Dynamic Behavior of Pure Squeeze Films in Narrow Porous Bearings

1974 ◽  
Vol 96 (3) ◽  
pp. 361-364 ◽  
Author(s):  
P. R. K. Murti
Keyword(s):  
Dynamic Behavior ◽  
Cyclic Load ◽  
Journal Bearing ◽  
Load Capacity ◽  
Squeeze Film ◽  
Closed Form Expression ◽  
Cyclic Loads ◽  
Eccentricity Ratio ◽  
Form Expression ◽  
Bearing Material

The dynamic behavior of squeeze film in a narrow porous journal bearing under a cyclic load is analyzed. A thin-walled bearing with a nonrotating journal is considered and a closed form expression for the pressure distribution is derived. The locus of the journal center is found by numerical methods and it is established with an example that actual contact between the journal and bearing can be avoided by appropriate design of the bearing. Consequently, it is proved that pure squeeze films have a load capacity only under cyclic loads. The analysis also reveals that the permeability of the bearing material and the wall thickness of the bearing influence significantly the operating eccentricity ratio.

The thermal capillary migration properties and controlling technique of ferrofluids

2017 ◽  
Vol 231 (11) ◽  
pp. 1441-1449 ◽  
Author(s):  
Qingwen Dai ◽  
Wei Huang ◽  
Jingqiu Wang ◽  
Xiaolei Wang
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Saturation Magnetization ◽  
Experimental Results ◽  
Migration Behavior ◽  
Thermal Gradients ◽  
Cold Regions ◽  
External Forces

The thermal capillary migration describes a phenomenon where the thermal gradients on the surface drive a liquid to flow from warm to cold regions in the absence of external forces. In industry, it is of great importance to prevent the migration since it would lead to lubricant starvation on the moving components. In this paper, ferrofluids are employed to control the migration. The influence of external magnetic field on the migration of ferrofluids is studied. The effects of volume and saturation magnetization of ferrofluids are also investigated. Experimental results demonstrate that the external magnetic field intensities have a significant obstruction effect on the migration behavior. An effective method using electromagnet to control the migration and re-concentrate the migrated lubricant is proposed.

Temperatur- und Konzentrationsabhängigkeit der 115In-Knightshift im flüssigen In-Mn-System

1990 ◽  
Vol 45 (7) ◽  
pp. 851-856
Author(s):  
I. Senel ◽  
D. Quitmann
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Moments ◽  
Metallic Alloys ◽  
Experimental Results

AbstractNMR measurements of the 115In-Knightshift and the linewidth in liquid In-Mn are reported. They were carried out in an external magnetic field of about 4.0 T at concentrations 0, 3, and 6 at.% Mn at temperatures from 400 K to 1300 K. According to our experimental results there are no localized magnetic moments in the liquid In-Mn-system. The experimental results are discussed in the framework of theories on metallic alloys.

scholarly journals Switching of perpendicularly polarized nanomagnets with spin orbit torque without an external magnetic field by engineering a tilted anisotropy

2015 ◽  
Vol 112 (33) ◽  
pp. 10310-10315 ◽  
Author(s):  
Long You ◽  
OukJae Lee ◽  
Debanjan Bhowmik ◽  
Dominic Labanowski ◽  
Jeongmin Hong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Data Storage ◽  
Easy Axis ◽  
Film Plane ◽  
The Other ◽  
Spin Orbit ◽  
Applied Current ◽  
Density Data ◽  
Magnetic Easy Axis

Spin orbit torque (SOT) provides an efficient way to significantly reduce the current required for switching nanomagnets. However, SOT generated by an in-plane current cannot deterministically switch a perpendicularly polarized magnet due to symmetry reasons. On the other hand, perpendicularly polarized magnets are preferred over in-plane magnets for high-density data storage applications due to their significantly larger thermal stability in ultrascaled dimensions. Here, we show that it is possible to switch a perpendicularly polarized magnet by SOT without needing an external magnetic field. This is accomplished by engineering an anisotropy in the magnets such that the magnetic easy axis slightly tilts away from the direction, normal to the film plane. Such a tilted anisotropy breaks the symmetry of the problem and makes it possible to switch the magnet deterministically. Using a simple Ta/CoFeB/MgO/Ta heterostructure, we demonstrate reversible switching of the magnetization by reversing the polarity of the applied current. This demonstration presents a previously unidentified approach for controlling nanomagnets with SOT.

Paper 10: A Hydrodynamic Pocket Journal Bearing

1969 ◽  
Vol 184 (12) ◽  
pp. 70-74
Author(s):  
D. F. Sheldon ◽  
J. P. O'Donoghue ◽  
C. J. Hooke
Keyword(s):  
High Pressure ◽  
Journal Bearing ◽  
Load Capacity ◽  
Control Device ◽  
Experimental Results ◽  
Alternative Mode ◽  
Hydrostatic Bearing ◽  
Operating Range ◽  
Mode Of Operation ◽  
Return Valve

The authors present theoretical and experimental results for a hydrodynamic pocket bearing. The bearing has a geometry similar to that of a conventional hydrostatic bearing, but no control device is incorporated in the supply line other than a non-return valve which prevents the leakage of fluid from those pockets where a pressure is generated. The load capacity of such bearings is greater than that of a circumferentially grooved hydrostatic bearing over the operating range of eccentricity tested by the authors, and is much greater than that of two short hydrodynamic bearings equal to the side sealing lands. Because of this the bearing offers a useful alternative mode of operation for a bearing (externally pressurized) which suffers a loss of its high-pressure oil supply.

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