The design of eccentricity ratio, relative clearance and length-to-diameter ratio of water-lubricated journal bearings under different working conditions

The steady state operational performance of gas-lubricated porous journal bearings is analyzed by using a numerical iterative method. Results are obtained, and presented in charts and tables, for the length-to-diameter ratio values of 1, 2, and 3; the eccentricity ratio values of 0.2, 0.4, 0.6, and 0.8; the compressibility number from 0 to 10; and several values of the feeding parameter and the supply-to-ambient pressure ratio commonly found in applications.

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Theoretical and experimental analysis of a water-lubricated rubber journal bearing with a large aspect ratio

Industrial Lubrication and Tribology ◽

10.1108/ilt-10-2019-0440 ◽

2020 ◽

Vol 72 (6) ◽

pp. 797-803

Author(s):

Zhiming Zhao ◽

Rui Zhang

Keyword(s):

Aspect Ratio ◽

Liquid Film ◽

Journal Bearings ◽

Diameter Ratio ◽

Hydrodynamic Characteristics ◽

Large Aspect Ratio ◽

Content Type ◽

Large Length ◽

Theoretical Results ◽

Length To Diameter Ratio

Purpose The hydrodynamic characteristics of liquid film for bearings, especially water-lubricated bearings with a large length-to-diameter ratio, affect the dynamics behavior of rotor bearing systems. The purpose of this study is to carry out theoretical analysis and experiments to determine the hydrodynamic characteristics of water-lubricated journal bearings. Design/methodology/approach The finite difference method is adopted for the simulation of the characteristics of water-lubricated bearings. The comparison results between water-lubricated bearings with and without grooves, as well as with and without the consideration of the effects of rubber deformation, are presented. The test bearings, test bench, and monitoring system, especially the force exciter for the bearing experiment, are presented. Dynamic coefficient identification verification experiments were performed in different working situations. The obtained results include the calibration of magnetic force, two kinds of excitation, vibration data of the rotor system and dynamic coefficients. Findings The theoretical results demonstrate that the hydrodynamic effect was obvious when the speed was increased and that the water film had improved capability at a working speed of 1800 rpm. The identification results reveal the lubrication situation of the test bearing under low-speed and high-load conditions. Moreover, it was found that the liquid film was not continuous at low speeds. Originality/value The theoretical results can lead to the enhancement of the design level of water-lubricated rubber journal bearings with a large aspect ratio. The experimental results can lead to the improvement of the dynamic behavior design of rotor systems supported using water-lubricated bearings with a large length-to-diameter ratio.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.642.242 ◽

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.

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High-Speed Motion Picture Camera Experiments of Cavitation in Dynamically Loaded Journal Bearings

Journal of Lubrication Technology ◽

10.1115/1.3254639 ◽

1983 ◽

Vol 105 (3) ◽

pp. 446-452 ◽

Cited By ~ 19

Author(s):

B. O. Jacobson ◽

B. J. Hamrock

Keyword(s):

Working Conditions ◽

Power Loss ◽

High Speed ◽

Journal Bearings ◽

Diameter Ratio ◽

High Speed Camera ◽

Surface Material ◽

Dynamically Loaded ◽

Dynamic Eccentricity ◽

Experimental Findings

It is important to know when and where cavitation occurs in bearings because cavitation has an effect on both the power loss and stability of the bearing. A bearing without cavitation can very well be unstable (vibrating) for the same working conditions where a cavitating bearing is stable. A high-speed camera was used to investigate cavitation in dynamically loaded journal bearings. The length-diameter ratio of the bearing, the speeds of the shaft and bearing, the surface material of the shaft, and the static and dynamic eccentricity of the bearing were varied. The results reveal not only the appearance of gas cavitation, but also the development of previously unsuspected vapor cavitation. Analysis is given to support the experimental findings for both gas and vapor cavitation.

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An Adiabatic Solution of Misaligned Journal Bearings

Journal of Tribology ◽

10.1115/1.3261041 ◽

1985 ◽

Vol 107 (2) ◽

pp. 263-267 ◽

Cited By ~ 31

Author(s):

M. O. A. Mokhtar ◽

Z. S. Safar ◽

M. A. M. Abd-El-Rahman

Keyword(s):

Thermal Effects ◽

Journal Bearings ◽

Diameter Ratio ◽

Length To Diameter Ratio

The paper presents an adiabatic analysis of misaligned journal bearings. The misalignment is allowed to vary in magnitude as well as in direction with respect to the bearing boundaries. Results are obtained for the case of a fixed journal axis with a bearing length to diameter ratio of unity. It is concluded that thermal effects are more pronounced for misaligned journal bearings

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CHF IN HIGH-PRESSURE REGIME FOR FORCED CONVECTION BOILING IN UNIFORMLY HEATED VERTICAL TUBES OF LOW LENGTH-TO-DIAMETER RATIO

Proceeding of International Heat Transfer Conference 7 ◽

10.1615/ihtc7.1100 ◽

1982 ◽

Cited By ~ 5

Author(s):

Yoshiro Katto ◽

S. Ashida

Keyword(s):

High Pressure ◽

Forced Convection ◽

Diameter Ratio ◽

Pressure Regime ◽

Vertical Tubes ◽

Length To Diameter Ratio

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Optimized growth of high length-to-diameter ratio Lu2O3 single crystal fibers by the LHPG method

CrystEngComm ◽

10.1039/d0ce01415j ◽

2021 ◽

Vol 23 (7) ◽

pp. 1657-1662

Author(s):

Na Zhang ◽

Yuqing Yin ◽

Jian Zhang ◽

Tao Wang ◽

Siyuan Wang ◽

...

Keyword(s):

Solid State ◽

Single Crystal ◽

High Power ◽

Diameter Ratio ◽

Solid State Lasers ◽

Crystal Fibers ◽

High Length ◽

Length To Diameter Ratio

Lu2O3 crystals have attracted intense attention due to their great potential in the field of high power solid-state lasers.

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EXPERIMENTAL STUDY ON FLAME PROPAGATION IN A STRAIGHT PIPE

Jurnal Teknologi ◽

10.11113/jt.v78.9568 ◽

2016 ◽

Vol 78 (8-3) ◽

Author(s):

Siti Zubaidah Sulaiman ◽

Rafiziana Md Kasmani ◽

A. Mustafa

Keyword(s):

Experimental Study ◽

Flame Propagation ◽

Experimental Work ◽

Diameter Ratio ◽

Straight Pipe ◽

Pipe Length ◽

Operating Condition ◽

Consistent Trend ◽

Length To Diameter Ratio

Flame propagation in a closed pipe with diameter 0.1 m and 5.1 m long, as well as length to diameter ratio (L/D) of 51, was studied experimentally. Hydrogen/air, acetylene/air and methane/air with stoichiometric concentration were used to observe the trend of flame propagation throughout the pipe. Experimental work was carried out at operating condition: pressure 1 atm and temperature 273 K. Results showed that all fuels are having a consistent trend of flame propagation in one-half of the total pipe length in which the acceleration is due to the piston-like effect. Beyond the point, fuel reactivity and tulip phenomenon were considered to lead the flame being quenched and decrease the overpressures drastically. The maximum overpressure for all fuels are approximately 1.5, 7, 8.5 barg for methane, hydrogen, and acetylene indicating that acetylene explosion is more severe.

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Roller Skewing Behavior in Roller Bearings

Journal of Lubrication Technology ◽

10.1115/1.3253206 ◽

1982 ◽

Vol 104 (3) ◽

pp. 311-320

Author(s):

L. J. Nypan

Keyword(s):

Diameter Ratio ◽

Radial Load ◽

Outer Race ◽

Roller Bearings ◽

Length To Diameter Ratio

Measurements of roller skewing of a 1.15 length to diameter ratio roller in 118 mm bore roller bearings of 0.18 and 0.21 mm (0.0073 and 0.0083 in.) clearance operating with a 4450 N (1000 lb) radial load at shaft speeds of 4000, 8000, and 12,000 rpm with outer race misalignment of 0, 0.5, and −0.5 deg are reported.

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The supersonic and low-speed flows past circular cylinders of finite length supported at one end

Journal of Fluid Mechanics ◽

10.1017/s0022112062000270 ◽

1962 ◽

Vol 12 (3) ◽

pp. 367-387 ◽

Cited By ~ 15

Author(s):

D. M. Sykes

Keyword(s):

Mach Number ◽

Finite Length ◽

Central Region ◽

Diameter Ratio ◽

Circular Cylinders ◽

Form Drag ◽

Drag Coefficients ◽

Low Speed ◽

Flow Past ◽

Length To Diameter Ratio

The flow past circular cylinders of finite length, supported at one end and lying with their axes perpendicular to a uniform stream, has been investigated in a supersonic stream at Mach number 1.96 and also in a low-speed stream. In both stream it was found that the flow past the cylinders could be divided into three regions: (a) a central region, (b) that near the free end of the cylinder, and (c) that near the supported end. The locations of the second and third regions were found to be almost independent of the cylinder length-to-diameter ratio, provided that this exceeded 4, while the flow within and the extent of the first region were dependent on this ratio. Form-drag coefficients determined in the central region in the supersonic flow were in close agreement with the values determined at the same Mach number by other workers. In the low-speed flow the local form-drag coefficients were dependent on length-to-diameter ratio and were always less than that of an infinite-length cylinder at the same Reynolds number.

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