An Adiabatic Solution of Misaligned Journal Bearings

1985 ◽  
Vol 107 (2) ◽  
pp. 263-267 ◽  
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

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

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.

Analysis of the Steady State Characteristics of Gas-Lubricated, Porous Journal Bearings

1975 ◽  
Vol 97 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Dah-chen Sun
Keyword(s):  
Steady State ◽  
Iterative Method ◽  
Ambient Pressure ◽  
Pressure Ratio ◽  
Journal Bearings ◽  
Diameter Ratio ◽  
Operational Performance ◽  
Eccentricity Ratio ◽  
Length To Diameter Ratio

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.

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

CrystEngComm ◽  
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.

EXPERIMENTAL STUDY ON FLAME PROPAGATION IN A STRAIGHT PIPE

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. 

Roller Skewing Behavior in Roller Bearings

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.

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

1962 ◽  
Vol 12 (3) ◽  
pp. 367-387 ◽  
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.

Numerical Analysis on the Electrical Performance of Microstructured Environmentally-Friendly Electrical Contact Material Ag/SnO2

2013 ◽  
Vol 419 ◽  
pp. 355-359
Author(s):  
Lei Wang ◽  
Wei Li Liu ◽  
Le Sheng Chen
Keyword(s):  
Numerical Simulation ◽  
Electrical Contact ◽  
Environmentally Friendly ◽  
Weight Percent ◽  
Diameter Ratio ◽  
Electrical Performance ◽  
Structural Parameter ◽  
Contact Material ◽  
Electrical Contact Material ◽  
Length To Diameter Ratio

The paper analyzes the influence of structural parameters on the electrical performance of the microstructured environmentally-friendly electrical contact material Ag/SnO2 by using numerical simulation method.The numerical results show that the reisitivity of fiber-like electrical contact material Ag/SnO2 is significantly reduced compared with the resistivity of Ag/SnO2 adding reinforcing nanoparticles in the traditional way.So the fiber-like electrical contact material Ag/SnO2 exhibits higher conductivity in macro. On further analysis, we learn that the resistivity of fibrous electrical contact materials is related to weight percent of reinforced phase, and micro-structural parameter of length to diameter ratio. The resistivity increases as weight percent of reinforced phase increases,and decreases non-linearly with micro-structural parameter of length to diameter ratio increasing.This demonstrates that numerical simulation is one of effective methods for analysis of the electrical performance of the microstructured electrical contact material.

scholarly journals A new method for calculating the sonic conductance of airflow through a short-tube orifice

2017 ◽  
Vol 9 (2) ◽  
pp. 168781401668726 ◽  
Author(s):  
Fan Yang ◽  
Gangyan Li ◽  
Dawei Hu ◽  
Toshiharu Kagawa
Keyword(s):  
Flow Rate ◽  
Critical Pressure ◽  
Pressure Ratio ◽  
Momentum Equation ◽  
Diameter Ratio ◽  
Test Method ◽  
Theoretical Formula ◽  
Engineering Applications ◽  
Short Tube ◽  
Length To Diameter Ratio

In this study, we proposed a method for calculating the sonic conductance of a short-tube orifice. First, we derived a formula for calculating the sonic conductance based on a continuity equation, a momentum equation and the definition of flow-rate characteristics. The flow-rate characteristics of different orifices were then measured using the upstream constant-pressure test method in ISO 6358. Based on these test data, the theoretical formula was simplified using the least squares fitting method, the accuracy of which was verified experimentally. Finally, the effects of the diameter ratio, the length-to-diameter ratio and the critical pressure ratio were analysed with reference to engineering applications, and a simplified formula was derived. We conclude that the influence of the diameter ratio is greater than that of the length-to-diameter ratio. When the length-to-diameter ratio is <5, its effect can be neglected. The critical pressure ratio has little effect on the sonic conductance of a short-tube orifice, and it can be set to 0.5 when calculating the sonic conductance in engineering applications. The formula proposed in this study is highly accurate with a mean error of <3%.

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