Effect of Groove Textures on the Performances of Gaseous Bubble in the Lubricant of Journal Bearing

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
F. M. Meng ◽  
L. Zhang ◽  
T. Long
Keyword(s):  
Journal Bearing ◽  
Bubble Radius ◽  
Groove Depth ◽  
Cycle Period ◽  
Collapse Pressure ◽  
Bubble Pressure ◽  
Collapse Temperature ◽  
Gaseous Bubble ◽  
Length Width ◽  
Gaseous Bubbles

Effects of groove textures on the performances for gaseous bubbles in the lubricant used for a textured journal bearing is studied under the consideration of thermal effect of lubricant. The Reynolds, energy, and Rayleigh–Plesset (RP) equations are solved simultaneously for simulating the behavior of the bubble. Numerical results show that the gaseous bubble radius shows a nonlinearly oscillation in a full cycle period, and high bubble pressure and temperature appear when the bubble collapses. Moreover, appropriately choosing groove length, width, or interval can reduce the maximum radius, collapse pressure, and collapse temperature of the bubble. There exists a critical groove depth minimizing the bubble pressure and temperature.

Operation Parameters' Effect on Gaseous Bubbles in Lubricant of Groove Textured Journal Bearing

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
F. M. Meng ◽  
L. Zhang ◽  
T. Long
Keyword(s):  
Journal Bearing ◽  
Computer Code ◽  
Diameter Ratio ◽  
Inlet Temperature ◽  
Bubble Behavior ◽  
Collapse Pressure ◽  
Shaft System ◽  
Operation Parameter ◽  
Gaseous Bubble ◽  
Gaseous Bubbles

Operation parameter influences on the behavior of the gaseous bubble in the lubricant for a groove textured journal bearing are studied under the consideration of the thermal effect of the bearing–shaft system. The influence is analyzed by simultaneously solving Rayleigh–Plesset (RP), energy, and Reynolds equations. The computer code for the analyzing the bubble behavior is validated. Numerical results show that appropriately increasing the width–diameter ratio of the bearing and rotational speed of the shaft, or decreasing the applied load and inlet temperature of the lubricant, can decrease the maximum radius, collapse pressure, and temperature of the bubble.

Characteristics of Herringbone-Grooved, Gas-Lubricated Journal Bearings

1965 ◽  
Vol 87 (3) ◽  
pp. 568-576 ◽  
Author(s):  
J. H. Vohr ◽  
C. Y. Chow
Keyword(s):  
Differential Equation ◽  
Journal Bearing ◽  
Groove Depth ◽  
Radial Force ◽  
Journal Bearings ◽  
Speed Ratio ◽  
Plain Bearing ◽  
Relative Speed ◽  
Whirl Speed ◽  
Limiting Case

A differential equation is obtained for the smoothed “overall” pressure distribution around a herringbone-grooved, gas-lubricated journal bearing operating with a variable film thickness. The equation is based on the limiting case of an idealized bearing for which the number of grooves approaches an infinite number. A numerical solution to the differential equation is obtained valid for small eccentricities. This solution includes the case where the journal is undergoing steady circular whirl. In addition to the usual plain bearing parameters L/D, Λ, and whirl speed ratio ω3/(ω1 + ω2), the behavior of a grooved bearing also depends on four additional parameters: The groove angle β, the relative groove width α, the relative groove depth H0, and a compressibility number, Λs, which is based on the relative speed between the grooved and smooth members of the bearing. Results are presented showing bearing radial force and attitude angle as functions of β, α, H0, Λs, Λ, and whirl speed ratio.

Geometry and Speed Effects on the Performance of the Herringbone Grooved Gas Lubricated Journal Bearing

2005 ◽  
Author(s):  
D. J. Foster
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Groove Depth ◽  
Bearing Surface ◽  
Static Stiffness ◽  
Groove Pattern ◽  
Land Width

The plain gas lubricated journal bearing is dynamically unstable. The addition of grooving on the bearing surface has been found to overcome this instability. In particular, the herringbone groove pattern has been found to provide damping with increase of static stiffness. The effect of the available geometry characteristics on performance is computed from solution of the compressible Reynolds equation. The geometry features examined are groove angle, and the ratios:- groove depth to clearance, groove-to-land width, axial groove length to bearing length and bearing eccentricity. The performance is determined over a range of compressibility numbers.

Variation of lubricant distribution across the radial direction in a journal bearing

2021 ◽  
pp. 1-20
Author(s):  
Shanshan Wei ◽  
Yuri Kligerman ◽  
Roman Goltsberg ◽  
Izhak Etsion
Keyword(s):  
Film Thickness ◽  
Radial Direction ◽  
Journal Bearing ◽  
Groove Depth ◽  
Cfd Analysis ◽  
Two Phase ◽  
Proposed Model ◽  
Inlet Tube ◽  
Cavitation Region ◽  
Computational Fluid Dynamics Cfd

Abstract A Computational Fluid Dynamics (CFD) analysis of two-phase flow was used to obtain the distribution of lubricant in a journal bearing, including inlet tube and groove. It was found that for an incomplete starting film, the oil spread-length varies along the groove depth and film thickness. The magnitude of variation was found to be independent of the inlet mass flow rate. Numerical simulations of the proposed model show that in the cavitation region the streamlets do not fill the entire film thickness. The present numerical model agrees with experimental observations.

Numerical simulation of traveling bubble cavitation

2006 ◽  
Vol 16 (4) ◽  
pp. 393-416 ◽  
Author(s):  
Sunil Mathew ◽  
Theo G. Keith Theo G. Keith ◽  
Efstratios Nikolaidis
Keyword(s):  
Cavitation Bubble ◽  
Bubble Radius ◽  
Random Variable ◽  
Bubble Collapse ◽  
Maximum Pressure ◽  
Local Pressure ◽  
New Approach ◽  
Content Type ◽  
Collapse Pressure ◽  
Bubble Cavitation

PurposeThe purpose is to present a new approach for studying the phenomenon of traveling bubble cavitation.Design/methodology/approachA flow around a rigid, 2D hydrofoil (NACA‐0012) with a smooth surface is analyzed computationally. The Rayleigh‐Plesset equation is numerically integrated to simulate the growth and collapse of a cavitation bubble moving in a varying pressure field. The analysis is performed for both incompressible and compressible fluid cases. Considering the initial bubble radius as a uniformly distributed random variable, the probability density function of the maximum collapse pressure is determined.FindingsThe significance of the liquid compressibility during bubble collapse is illustrated. Furthermore, it is shown that the initial size of the bubble has a significant effect on the maximum pressure generated during the bubble collapse. The maximum local pressure developed during cavitation bubble collapse is of the order of 104 atm.Research limitations/implicationsA single bubble model that does not account for the effect of neighboring bubbles is used in this analysis. A spherical bubble is assumed.Originality/valueA new approach has been developed to simulate traveling bubble cavitation by interfacing a CFD solver for simulating a flow with a program simulating the growth and collapse of the bubble. Probabilistic analysis of the local pressure due to bubble collapse has been performed.

Monte Carlo Simulation of the Manufacturing Tolerance of FDBs to Identify the Sensitive Design Variables Affecting the Performance of a Disk-Spindle System

2014 ◽  
Author(s):  
J. H. Lee ◽  
M. H. Lee ◽  
H. K. Jang ◽  
G. H. Jang
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Journal Bearing ◽  
Fluid Dynamic ◽  
Critical Mass ◽  
Groove Depth ◽  
Friction Torque ◽  
Spindle System ◽  
Manufacturing Tolerance ◽  
Design Variables

This research investigates the Monte Carlo simulation of manufacturing tolerance of FDBs to identify the sensitive design variables for the friction torque of fluid dynamic bearings (FDBs) and the critical mass of disk-spindle system supported by FDBs. We analyze the characteristics according to design variables of FDBs and it shows that the clearance of journal bearing is most sensitive design variable of both friction torque and critical mass. Also the groove to groove and ridge ratio and groove depth of grooved journal bearing which are manufactured by ECM are also sensitive to determine the friction torque and the critical mass of the FDBs, respectively. This research can be utilized to manage manufacturing tolerance to maintain the consistent performance of FDBs and a disk-spindle system in a HDD.

Boiling Heat Transfer Characteristics and Film Boiling Collapse Temperature Through the Two-Dimensional Temperature Field Measurement: Examination of Condition in High Liquid Subcooling Condition

2016 ◽  
Author(s):  
Hajime Takeuchi ◽  
Hiroyasu Ohtake ◽  
Masahiro Ueno ◽  
Hiroshi Washida ◽  
Koji Hasegawa
Keyword(s):  
Boiling Heat Transfer ◽  
Liquid Velocity ◽  
Atmospheric Condition ◽  
Film Boiling ◽  
Back Side ◽  
Heat Transfer Characteristics ◽  
Silver Plate ◽  
Impingement Jet ◽  
Collapse Temperature ◽  
Length Width

The behavior of rewetting on a high superheated and dry surface, focusing on rewetting temperature just as collapse of saturated and subcooled film boiling was investigated experimentally. Saturated and subcooled impingement jet experiments were conducted by using a silver plate with 40.0 mm × 40.0 mm (length × width) and the distilled water at atmospheric condition. The liquid subcooling was 0, 10, 20, 30, 40, 50, and 75K, respectively. Temperature of the test heater was measured by using a infrared thermometer from a back side of it. Although the liquid velocity and liquid subcooling change, the sputtering temperature, i.e., rewetting initiation temperature, was close to 200 °C predicted by Nishio’s correlation.

Performance of a novel foil journal bearing with surface micro-grooved top foil

2017 ◽  
Vol 232 (9) ◽  
pp. 1126-1139 ◽  
Author(s):  
Jiajia Yan ◽  
Guanghui Zhang ◽  
Zhansheng Liu ◽  
Jingming Zhao ◽  
Liang Xu
Keyword(s):  
Thick Plate ◽  
Journal Bearing ◽  
Dynamic Properties ◽  
Load Capacity ◽  
Groove Depth ◽  
Machining Process ◽  
Foil Thickness ◽  
Foil Bearing ◽  
Direct Stiffness ◽  
Groove Structure

To improve the performance of foil bearing including load capacity and stability, the surface micro groove structure on top foil is proposed, which is possible with the development of surface micro machining process. The micro groove structure on top foil can be processed by laser surface process, chemical etching, mechanical grinding, etc. This paper proposes a novel bump-type gas foil journal bearing with surface micro-grooved top foil and investigates the influence of micro groove depth on bearing performance theoretically. A modified pressure governing equation is established with the consideration of gas rarefaction, and the performance of the bearing is analyzed based on numerical simulation. By considering the variation of top foil thickness for surface micro groove, the load capacities with and without gas rarefaction considered are obtained by finite difference method, where the 2D thick plate model is adopted for the top foil. By employing the perturbation method, the force coefficients of this type foil bearing are calculated. The results indicate this novel foil journal bearing with surface micro-grooved top foil can decrease the end leakage and increase pressure around load domain efficiently. The load capacity and dynamic properties are improved. Moreover, with the increment of micro groove depth, the load capacity and direct stiffness are reinforced further. For the foil journal bearing with a micro groove depth of 8 µm on top foil, the load capacity and direct stiffness increase by about 11.89% and 11.87%, respectively, compared with traditional foil journal bearing.

Static performance of the aerostatic journal bearing with grooves

2019 ◽  
Vol 234 (7) ◽  
pp. 1114-1130
Author(s):  
Xinglong Chen ◽  
James K Mills ◽  
Gang Bao
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Journal Bearing ◽  
Load Capacity ◽  
Groove Depth ◽  
Load Force ◽  
Orifice Diameter ◽  
Geometrical Parameters ◽  
Gas Flow Rate ◽  
Static Performance

Aerostatic bearings are widely employed in precision machines due to their properties of low friction, low heat conduction, and long-life operation. In this work, static performance of the journal bearing with rectangular grooves is investigated numerically. The effect of geometrical parameters such as axial groove length [Formula: see text], circumferential groove length [Formula: see text], orifice diameter df, groove depth gh, misalignment angles [Formula: see text] and [Formula: see text] on the load capacity [Formula: see text], stiffness [Formula: see text], and gas flow rate [Formula: see text] are analyzed systematically. The resistance network method (RNM) is utilized to solve the Reynolds equation required in the analysis. Performance parameters including pressure distribution P, load force [Formula: see text], stiffness [Formula: see text], and gas flow rate [Formula: see text] are examined in the simulations. It is revealed from the simulations that the proper value of axial groove length [Formula: see text] to obtain a better static performance varies from 1/8 to 1/2 when df varies between 0.11 and 0.29 mm, respectively. Therefore, a larger load force and stiffness can be obtained if [Formula: see text] is chosen to be 1/4, when diameter of the bearing orifice df equals 0.17 mm. It is also suggested that [Formula: see text] be chosen from the range of 1/6 and 1/3 to obtain a better static performance and a smaller gas flow rate. [Formula: see text] decreases with an increase in df when [Formula: see text] is set to be 1/8. However, the load force [Formula: see text] increases with an increase in df when [Formula: see text] varies from 3/8 to 1/2. [Formula: see text] has a significant influence on the changes of [Formula: see text] with df when [Formula: see text] is set to be constant. Therefore, df should be selected according to [Formula: see text] for an optimal design. The increase of misalignment angle [Formula: see text] leads to an increase in the load force [Formula: see text]. [Formula: see text] has little influence on the load force [Formula: see text]. Misalignment angles [Formula: see text] and [Formula: see text] have little influence on stiffness [Formula: see text] and gas flow rate [Formula: see text]. Therefore, it is preferable if [Formula: see text] is larger than 0 rad.

scholarly journals Structural Design and Optimization of Herringbone Grooved Journal Bearings Considering Turbulent

2022 ◽  
Vol 12 (1) ◽  
pp. 485
Author(s):  
Xichun Liu ◽  
Wei Chen
Keyword(s):  
Liquid Metal ◽  
High Performance ◽  
Journal Bearing ◽  
Structural Parameters ◽  
Constant Width ◽  
Dynamic Performance ◽  
Helix Angle ◽  
Groove Depth ◽  
Journal Bearings ◽  
Design And Optimization

In order to improve the performance of the traditional constant-width herringbone grooved journal bearing in a computed tomography tube under a high-temperature environment, the present study designed a convergent herringbone grooved journal bearing (HGJB) structure lubricated by liquid metal. The bearing oil film thickness and the Reynolds equation considering the influence of turbulence are established and solved by using the finite difference method in the oblique coordinate system. The performance of the two bearings was compared, and the static and dynamic performance change trends of the two bearing structures under different eccentricities were systematically studied. The results show that the convergent herringbone grooved journal bearings are superior to the constant-width herringbone grooved journal bearings in terms of bearing capacity and stiffness coefficient. At the same time, the influence of structural parameters, such as the number of grooves, helix angle, groove to ridge ratio, groove depth on the performance of the constant-width herringbone grooved journal bearings, and the convergent herringbone grooved journal bearings was studied. Finally, we conclude that the performance of the convergent herringbone grooved journal bearings is optimal when the number of grooves is 15–20, the helix angle is 30–45°, the ratio of the groove to ridge is 1, and the groove depth is 0.02 mm −0.024 mm. This research has provided the thinking and reference basis for the design of liquid metal bearings for high-performance CT equipment.

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