On the Optimum Groove Geometry for Herringbone Grooved Journal Bearings

2006 ◽  
Vol 128 (3) ◽  
pp. 585-593 ◽  
Author(s):  
A. M. Gad ◽  
M. M. Nemat-Alla ◽  
A. A. Khalil ◽  
A. M. Nasr
Keyword(s):  
Groove Depth ◽  
Radial Force ◽  
Journal Bearings ◽  
Friction Torque ◽  
Performance Characteristics ◽  
Width Ratio ◽  
Geometrical Parameters ◽  
Thrust Bearings ◽  
Circular Groove ◽  
Groove Profile

Recently, herringbone-grooved journal bearings have had important applications in miniature rotating machines. The scribed grooves, on either the rotating or stationary member of the bearing, can pump the lubricant inward, which generates supporting stiffness and improves the dynamic stability, especially for concentric operation. Most of the previous investigations that dealt with herringbone grooved journal bearings and grooved thrust bearings were theoretical. Few experimental attempts for the investigation of the performance characteristics of herringbone grooved journal bearings (HGJBs) and grooved thrust bearings have been done. All these investigations concentrated on rectangular and circular groove profiles of HGJBs. In order to improve the performance characteristics of HGJBs, a new design of the groove profile, the beveled-step groove profile, is introduced. The introduced groove profile is capable of increasing the pressure recovery at the divergence of the flow over the step. In addition, it increases the amount of oil pumped inward over the circular groove profile. Optimization processes were carried out experimentally, in order to obtain the optimal geometry of the introduced groove profile. The optimum geometrical parameters of the groove (groove angle α, groove width ratio β, and groove depth ratio Γ) are 29deg, 0.5, and 2.0, respectively, which give maximum radial force and maximum radial stiffness of the beveled-step HGJB. In order to check the effectiveness of the introduced beveled-step groove profile, the obtained results were compared with that for rectangular groove profile. The comparison shows that the introduced beveled-step HGJBs have higher radial force, higher load carrying capacity, and lower friction torque than the rectangular HGJBs.

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.

Ultimate Strength of Hull Structural Stiffened Plate with Grooving Corrosion Damage under Uniaxial Compression

2020 ◽  
pp. 1-11
Author(s):  
Yufan Zhu ◽  
Yan Zhang ◽  
Fei Du
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Corrosion Damage ◽  
Groove Depth ◽  
Assessment Method ◽  
Welding Residual Stress ◽  
Stiffened Plates ◽  
Width Ratio ◽  
Geometrical Parameters ◽  
Geometric Imperfection

Grooving corrosion results in a decrease in the ability of the structure to resist external loads. In the present study, a new assessment method was developed to investigate the ultimate loading capacity of stiffened plates with grooving corrosion damage. First, the basic parameters of stiffened plates (including model range, boundary condition, welding residual stress, initial geometric imperfection, and size of finite element) were assumed. Second, the influences of corrosion parameters and geometrical parameters of stiffened plates (such as finite element type, groove width, groove depth, groove depth-to-width ratio, plate flexibility, stiffener flexibility, and number of stiffeners) were analyzed. Third, based on the data analysis from a large number of nonlinear finite element analyses, the ultimate strength reduction formula of stiffened plates was derived. Last, the correctness of the formula was verified by ultimate strength experiment.

An Experimental Study of 3D Printed Herringbone Grooved Journal Bearings

2017 ◽  
Author(s):  
Elizabeth Rasmussen ◽  
Phillip Rudolph ◽  
Alexander Mamishev
Keyword(s):  
Low Cost ◽  
Large Body ◽  
Groove Depth ◽  
Journal Bearings ◽  
Dynamics Simulation ◽  
Width Ratio ◽  
Velocity Magnitude ◽  
Lubricant Flow ◽  
3D Printed ◽  
Alternative Choice

Herringbone grooved journal bearings are well known for their reliability and high rotor dynamic stability thresholds. While there is a large body of research surrounding the optimized groove geometry parameters, analysis on the material the groves are placed on has been mainly limited to metals. The ability to use plastic while maintaining desired qualities of reliability and stability is of great interest due to its light weight and low cost possibilities. The goal of the current study is to see if current technology limits on plastic 3D printed parts layer thickness inhibit lubricant flow, or if 3D printed parts can be used as an alternative choice in manufacturing journal bearings. The optimum geometries for square, circular, and beveled step groove profiles were 3D printed with layer thicknesses of 16, 50, 100, and 250 micrometers. Additionally, the effect of herringbone groove parameters such as groove width ratio, groove depth ratio, and groove angle were explored. Finally, a 2-dimentional Computational Fluid Dynamics simulation of a square, circular, and beveled step herringbone groove geometry velocity magnitude profiles are presented.

Static and Dynamic Characteristics of Oil Lubricated Beveled-Step Herringbone-Grooved Journal Bearings

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. M. Nemat-Alla ◽  
A. M. Gad ◽  
A. A. Khalil ◽  
A. M. Nasr
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Friction Torque ◽  
Experimental Results ◽  
Static And Dynamic Characteristics ◽  
Thrust Bearings ◽  
Rectangular Profile ◽  
The Stability

Recently, herringbone-grooved journal bearings (HGJBs) have important applications in high-speed rotating machinery. The groove action in pumping the lubricating fluid inward generates supporting stiffness and improves the stability of the bearing when operating concentrically. Several researchers have investigated the static and dynamic characteristics of HGJBs and grooved thrust bearings. Most of these investigations were theoretical and concentrated on HGJBs with rectangular-profile grooves. In the present work, the static and dynamic characteristics of the beveled-step HGJBs are experimentally investigated. The bearing attitude angle, pressure distribution, and bearing friction torque were measured on a hydrodynamic lubrication unit, and then the static and dynamic characteristics were determined. The obtained experimental results are compared to the obtained experimental results for plain journal bearing. The merits as well as the demerits of the groove profile were discussed through comparisons with plain journal bearings.

Performance of novel air foil thrust bearings with taper-groove on surface of top foil

2020 ◽  
Vol 235 (1) ◽  
pp. 79-92
Author(s):  
Hongyang Hu ◽  
Ming Feng
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Groove Depth ◽  
Friction Torque ◽  
Width Ratio ◽  
Local Dynamic ◽  
The Novel ◽  
Rarefaction Effect ◽  
Foil Thrust Bearing

To improve the load capacity of air foil thrust bearing, the micro taper-grooves on the surface of top foil was introduced and studied. A modified Reynolds equation considering the gas rarefaction effect was established, in which the Knudsen number was affected by the film thickness and pressure. A new bump stiffness model was built with the consideration of bump rounding, friction, and bending stiffness of foil. By considering the variation of gas film thickness, the load capacity, friction torque, and power loss of novel bearing with grooves were calculated by the finite difference method. Moreover, the effect law of groove parameters, groove shape and grooves number on the novel bearing performance was studied systematically. The results show that the predicted axial load capacity considering gas rarefaction effect is decreased slightly in smaller clearance and more consistent with the actual test data. The novel air foil thrust bearing with taper-groove can weaken the air end leakage and enhance the local dynamic pressure efficiently in the parallel portion of top foil, thus improving the static characteristics of bearing. For the novel air foil thrust bearing with taper-groove depth of 10 µm, the load capacity can be increased by about 13.33%, compared with traditional bearing. With the increments of taper-groove depth and length on top foil, the load capacity can be increased. However, the friction torque is decreased when there is a longer taper-groove in the circumferential direction. Meanwhile, the optimal groove width ratio is about 0.5, and the structure of multi-grooves is beneficial to the decreased friction torque. The validity of presented theoretical model has been verified by the literature data, and the results are expected to be helpful to bearing designers, researchers, and academicians concerned.

An experimental investigation of a microturbine simulated rotor supported on multileaf gas foil bearings with backing bump foils

2017 ◽  
Vol 232 (9) ◽  
pp. 1169-1180 ◽  
Author(s):  
Bo Zhang ◽  
Shemiao Qi ◽  
Sheng Feng ◽  
Haipeng Geng ◽  
Yanhua Sun ◽  
...  
Keyword(s):  
High Speed ◽  
Preliminary Test ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
System Stability ◽  
Test Rig ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Simulated System ◽  
First Time

Two multileaf gas foil journal bearings with backing bump foils and one set of gas foil thrust bearings were designed, fabricated, and used in a 100 kW class microturbine simulated rotor system to ensure stability of the system. Meanwhile, a preliminary test rig had been built to verify the simulated system stability. The rotor synchronous and subsynchronous responses were well controlled by using of the gas foil bearings. It is on the multileaf gas foil bearings with backing bump foils that the test was conducted and verified for the first time in open literatures. The success in the experiments shows that the design and fabrication of the rotor and the gas foil bearings can provide a useful guide to the development of the advanced high speed rotating machinery.

Investigation of the micropolar lubricant and thermal effects in the slot entry hybrid journal bearings

2017 ◽  
Vol 232 (11) ◽  
pp. 2103-2116 ◽  
Author(s):  
Pankaj Khatak ◽  
HC Garg
Keyword(s):  
Performance Analysis ◽  
Present Article ◽  
Thermal Effects ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Reliable Performance ◽  
Isothermal Characteristics

The present article studies the combined influence of the micropolar lubricant and thermal effects in the slot entry hybrid journal bearings. Bearing performance characteristics are computed by the concurrent solution of modified Reynolds, three-dimensional micropolar energy, and three-dimensional conduction equations. Thermohydrostatic characteristics of the slot entry hybrid journal bearings have been studied vis-à-vis isothermal characteristics. The results obtained numerically indicate that isoviscous assumption of the lubricant is incorrect and the bearing performance is significantly affected by the increase in temperature. Hence, it is essential to consider the thermal effects for the bearings operating with the micropolar lubricant for reliable performance analysis of the bearings.

scholarly journals On the evaluation of chicken egg shape variability

2008 ◽  
Vol 56 (5) ◽  
pp. 69-74 ◽  
Author(s):  
Miroslav Havlíček ◽  
Šárka Nedomová ◽  
Jana Simeonovová ◽  
Libor Severa ◽  
Ivo Křivánek
Keyword(s):  
Shape Index ◽  
Width Ratio ◽  
Geometrical Parameters ◽  
Fourier Descriptors ◽  
Shape Variation ◽  
Egg Volume ◽  
Maximum Width ◽  
Chicken Egg ◽  
Egg Shape ◽  
Elliptic Fourier Descriptors

Although recently reported models for determining egg shape are highly accurate, certain com­pli­ca­ted measurements or computations are to be performed. Thus relatively simple and attainable analysis methods of chicken egg shape variability were chosen and used for the purpose of presented research. Sample of 250 eggs of ISA BROWN strain was examined. Geometrical parameters were measured and calculated with following expression of their coefficient of variation – namely egg length 3.56 %, egg maximum width 2.84 %, shape index 3.80 %, surface area 5.08 %, and egg volume 7.23 %. The second method consisted in shape quantitative measuring by the score of the principal components of elliptic Fourier descriptors (EFDs). The first four principles components which could explain over 99 % of the egg shape variations were found to be very good measures of the monitored phenomenon. It was found that 87.41 % of the total shape variation can be accounted to length to width ratio. Usefulness and relevance of the shape index usage was confirmed.

scholarly journals Analysis of the effect of oil inlet size on the static performance characteristics of non-Newtonian lubricated hole-entry hybrid journal bearings

2021 ◽  
Vol 37 ◽  
pp. 522-531
Author(s):  
Haiyin Cao ◽  
Yu Huang ◽  
Youmin Rong ◽  
Hao Wu ◽  
Minghui Guo
Keyword(s):  
Finite Element Method ◽  
High Speed ◽  
Reynolds Equation ◽  
Journal Bearings ◽  
Performance Characteristics ◽  
Power Law Model ◽  
The Finite Element Method ◽  
Solution Strategy ◽  
Nonuniform Mesh ◽  
Static Performance

Abstract In this study, the influence of inlet pocket size on the static performance of non-Newtonian lubricated hole-entry hybrid journal bearings is theoretically analyzed. The oil film of the bearing is discretized into a nonuniform mesh containing the geometric characteristics of the oil inlet pocket, and the inlet pocket is treated as a micro-oil recess. The Reynolds equation is solved by the finite element method based on Galerkin's techniques, and a new solution strategy to solve the recess/pocket pressure is proposed. The power-law model is used to introduce the non-Newtonian effect. The results show that the static performance characteristics of this type of bearing are greatly affected by the pocket size at both zero speed and high speed.

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