Static Characteristics of Journal Bearings With Square Dimples

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Hiroo Taura ◽  
Satoru Kaneko
Keyword(s):  
Hydrodynamic Lubrication ◽  
Numerical Models ◽  
Experimental Studies ◽  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Conditions ◽  
Static Characteristics ◽  
Lubrication Performance

Surface texturing is a technique for improving frictional and hydrodynamic performances of journal bearings because microtextures can serve as reservoirs for oil or traps for debris and may also generate hydrodynamic pressure. Over the past two decades, many researchers have experimentally demonstrated that texturing of various tribological elements can reduce friction force and wear, contributing to improvement of lubrication performance. Some numerical studies have examined the hydrodynamic lubrication conditions and reported that surface texturing affects the static characteristics of journal bearings, such as their load carrying capacity and friction torque. However, the validity of these numerical models has not been confirmed because of a lack of experimental studies. This study proposes a numerical model that includes both inertial effects and energy loss at the edges of dimples on the surface of a journal bearing in order to investigate the bearing's static characteristics. Experimental verification of journal bearings is also conducted with a uniform square-dimple pattern on their full-bearing surface. The results obtained by the model agree well with those of experiment, confirming the model's validity. These results show that under the same operating conditions, textured bearings yield a higher eccentricity ratio and lower attitude angle than the conventional ones with a smooth surface. This tendency becomes more marked for high Reynolds number operating conditions and for textured bearings with a large number of dimples.

scholarly journals The effect of textured surfaces on the hydrodynamic pressure generation in journal bearings

2018 ◽  
Vol 204 ◽  
pp. 04006
Author(s):  
Muchammad ◽  
Mohammad Tauviqirrahman ◽  
Rizqy Amanullah Akbar ◽  
Fuad Hilmy ◽  
Jamari
Keyword(s):  
Journal Bearing ◽  
Fluid Dynamic ◽  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Journal Bearings ◽  
Hydrodynamic Performance ◽  
Textured Surfaces ◽  
Eccentricity Ratio ◽  
Lubrication Performance ◽  
Effect Of Surface

Surface texturing of the lubricated bearing has proven to improve the hydrodynamic performance. The present paper analyzed the effect of surface texturing on the covergent journal bearing with computational fluid dynamic (CFD) approach. The eccentricity ratio, the ratio of textured depth and surface area are the main parameter research. It was shown that for the eccentricity ratio of 0.2, the surface texturing improves the hydrodynamic performance lubrication by increasing the load support. On the otherwise, for the eccentricity ratio of 0.8, the surface texturing does not improve the lubrication performance, even under certain condition, it decreases the lubrication performance of journal bearing.

A Study of the Mechanism of Lubrication in Porous Journal Bearings: Effects of Dimensionless Oil-Feed Pressure on Static Characteristics Under Hydrodynamic Lubrication Conditions

1994 ◽  
Vol 116 (3) ◽  
pp. 606-611 ◽  
Author(s):  
Satoru Kaneko ◽  
Yasuhiro Ohkawa ◽  
Yuji Hashimoto
Keyword(s):  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Static Characteristics ◽  
Oil Film ◽  
Bearing Clearance ◽  
Feed Pressure ◽  
Angular Extent ◽  
Lubrication Conditions

The static characteristics of porous journal bearings under hydrodynamic lubrication conditions are theoretically investigated assuming that the oil is fed through their outside diameters under a small pressure. The angular extent of the oil film formed in the bearing clearance is numerically solved on the basis of the following postulate: when the oil film extent reaches steady state, the inflow of oil into the bearing clearance through the porous matrix due to the oil-feed pressure must make up for the oil leakage from the ends through the clearance gap and that into the porous matrix due to the hydrodynamic pressure in the film. Numerical results show that the dimensionless oil-feed pressure significantly influences the static characteristics. Experiments are also conducted for confirmation after the theoretical examination.

Numerical and Experimental Analyses of the Dynamic Characteristics of Journal Bearings With Square Dimples

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Hiroyuki Yamada ◽  
Hiroo Taura ◽  
Satoru Kaneko
Keyword(s):  
Numerical Analysis ◽  
Dynamic Characteristics ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Conditions ◽  
Shaft Speed ◽  
Static Characteristics ◽  
Stability Threshold ◽  
Dynamic Coefficients ◽  
Stiffness Coefficients

Numerous previous numerical studies have investigated the effect of surface texturing upon the static characteristics of journal bearings, including their load-carrying capacity and friction torque. In general, the dynamic characteristics of journal bearings are also important, since they are essential factors in predicting the vibration behavior of actual rotors supported by journal bearings. However, the effects of surface texture upon these dynamic characteristics have not been investigated through either numerical or experimental analysis. Thus, in the present study, such analyses were conducted to investigate the dynamic characteristics of textured journal bearings, such as their dynamic coefficients of oil film and the stability-threshold shaft speed supported by the bearings. Numerical analysis was done using a model that included inertial effects and energy loss; this model agreed well with experimental results concerning static characteristics from our previous study. Dynamic testing based on a sinusoidal-excitation method was also performed using textured journal bearings with uniform square dimples to verify the numerical results, which agreed qualitatively with those of experiment, confirming the validity of the numerical analysis. These results suggest that under the same operating conditions, the main effect of texturing upon the dynamic coefficients is to yield the cross-coupled stiffness coefficients with lower absolute values than the conventional ones with a smooth surface. The linear stability-threshold shaft speed of the rotor supported by the textured journal bearings became higher than that of a smooth bearing, mainly due to the reduction of cross-coupled stiffness coefficients. This tendency became more pronounced for high Reynolds number operating conditions and textured bearings with a large number of dimples.

Performance of Stern Tube Bearings under Different Lubrication and Operating Conditions

2009 ◽  
Author(s):  
Jan H. Andersen ◽  
Hiroyuki Sada ◽  
Seiji Yamajo
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Water Soluble ◽  
Analysis Tool ◽  
Test Rig ◽  
Experimental Performance ◽  
Shaft Alignment ◽  
Alignment Analysis

This paper presents the results of an investigation into the theoretical and experimental performance of oil lubricated journal bearings. DNV has developed a new calculation tool for the analysis of journal bearing performance as part of shaft alignment analysis. The results of the calculation tool have been compared to other research and analysis methods under static and dynamic conditions. In addition, white metal bearings were tested with decreasing Sommerfeld number until loss of hydrodynamic lubrication. The experiments were carried out in a bearing test rig and with three different lubricants, normal mineral oil, emulsifying oil, and water-soluble oil. The tests were done with increasing water content in the lubricant. Results from the test were compared with calculation using the DNV analysis tool.

Effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions

2020 ◽  
Vol 21 (3) ◽  
pp. 301
Author(s):  
Chongpei Liu ◽  
Wanyou Li ◽  
Xiqun Lu ◽  
Bin Zhao
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Asperity Contact ◽  
Adiabatic Flow ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Edge Wear ◽  
Journal Misalignment

The textures on the bushing surface have important effects on the performance of journal bearing. In this study, the effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions are investigated theoretically. The journal misalignment, asperity contact and thermal effects are considered, while the profile modifications due to running-in are neglected. The Winkler/Column model is used to calculate the elastic deformation of bushing surface and the adiabatic flow hypothesis is adopted to obtain the effective temperature of lubricating oil. The numerical solution is established by using finite difference and overrelaxation iterative methods, and the rupture zone of oil film is determined by Reynolds boundary conditions. The numerical results reveal that the double parabolic profiles with groove textures with proper location and geometric sizes can increase load carrying capacity and reduce friction loss under steady operating conditions, which effectively overcome the drawbacks of double parabolic profiles. This novel bushing profile may help to reduce the bushing edge wear and enhance the lubrication performance of journal bearing.

A Numerical Solution for the Hydrodynamic Lubrication of Finite Porous Journal Bearings

1973 ◽  
Vol 187 (1) ◽  
pp. 71-78 ◽  
Author(s):  
B. R. Reason ◽  
D. Dyer
Keyword(s):  
Numerical Solution ◽  
Numerical Method ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Approximate Solutions ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Variable Porosity ◽  
Present Solution

We present a numerical solution for the operating conditions of a hydrodynamic porous journal bearing. The numerical method allows for the possibility of variable porosity in the bearing matrix, but the solution has been achieved on the assumption of matrix homogeneity. The relation between the various bearing parameters have been shown for a variety of bearing geometries and permeabilities enabling the operating conditions for this type of bearing to be better appreciated. A comparison of the present solution with approximate solutions used by other authors has been made, which indicates the useful working range of the approximate solutions.

Influence of Donut-Shaped Bump on the Hydrodynamic Lubrication of Textured Parallel Sliders

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Hao Fu ◽  
Jinghu Ji ◽  
Yonghong Fu ◽  
Xijun Hua
Keyword(s):  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Hydrodynamic Pressure ◽  
Hydrodynamic Performance ◽  
Geometrical Parameters ◽  
Textured Surfaces ◽  
Bump Height ◽  
Lubrication Performance ◽  
Parallel Surfaces ◽  
Vertical Spacing

The influence of donut-shaped bump texture on the hydrodynamic lubrication performance for parallel surfaces is presented in this paper. A mathematical equation has been applied to express the shape of three-dimensional donut-shaped bump texture. Numerical simulation of the pressure distribution of lubricant between a textured slider and a smooth, moving slider has been performed to analyze the geometrical parameters' influence on the hydrodynamic performance for textured surfaces. The numerical results show that the convex of the donut-shaped bump provides a microstep slider, which can form a convergent wedge and build up hydrodynamic pressure. Optimum values of horizontal spacing and bump height are obtained to maximize the hydrodynamic pressure. It is also noted that the average pressure increases monotonically with the increase of bump radius, but decreases with the increase of vertical spacing and dimple depth, respectively.

scholarly journals Experimental studies and mathematical modeling on the effects of rapid airflow and baking temperature during baking

2020 ◽  
pp. 469
Author(s):  
Mazidah Mior Zakuan Azmi ◽  
Anvarjon Ahmedov ◽  
Farah Saleena Taip
Keyword(s):  
Heat Transfer ◽  
Volume Expansion ◽  
Numerical Models ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Transfer Model ◽  
Temperature Profiles ◽  
Convection Oven ◽  
Baking Process ◽  
Cake Baking

Rapid airflow in oven will influence the heat transfer in baking process therefore the purpose of this study is to experimentally and numerically investigate the effects of operating conditions on the heat transfer mechanism and volume expansion during baking. Cakes are baked in an air fryer and convection oven with constant speed 5.11 m/s and 0.88 m/s respectively at 150, 160, 170 °C in different baking times. A heat transfer model was defined to describe the influence of baking temperature on internal cake temperature by Fourier’s law. It was observed that the presence of rapid airflow (air fryer) and increment in oven temperature yielded an increase in volume expansion but produced a less moist product. Cakes baked in the presence of rapid airflow at 150 °C were moister but with little volume expansion in the cakes compared to convection oven-baked cakes. Significant correlation between the numerical models with experimental temperature profiles were recorded during complete cake baking process.

scholarly journals New Star-Like Surfacetexture for Enhanced Hydrodynamic Lubrication Performance

2017 ◽  
Vol 62 (3) ◽  
pp. 1863-1869
Author(s):  
M.S. Uddin ◽  
Y.W. Liu ◽  
S. Shankar
Keyword(s):  
Friction Coefficient ◽  
Numerical Modelling ◽  
Hydrodynamic Lubrication ◽  
Surface Texturing ◽  
Optimum Shape ◽  
Slider Bearing ◽  
Film Pressure ◽  
Texture Density ◽  
Lubrication Performance ◽  
Wedge Effect

Abstract This paper presents a numerical modelling and optimization of a new ‘star-like’ geometric texture shape with an aim to improve tribological performance. Initial studies showed that the triangle effect is the most dominant in reducing the friction. Motivated with this, a ‘star-like’ texture shape consisting of a series of triangular spikes around the centre of the texture is proposed. It is hypothesised that by increasing the triangular effect on a texture shape, the converging micro-wedge effect is expected to increase, hence increasing the film pressure and reducing the friction. Using the well-known Reynolds boundary conditions, numerical modelling of surface texturing is implemented via finite difference method. Simulation results showed that the number of apex points of the new ‘star-like’ texture has a significant effect on the film pressure and the friction coefficient. A 6-pointed texture at a texture density of 0.4 is shown to be the optimum shape. The new optimum star-like texture reduces the friction coefficient by 80%, 64.39%, 19.32% and 16.14%, as compared to ellipse, chevron, triangle and circle, respectively. This indicates the potential benefit of the proposed new shape in further enhancing the hydrodynamic lubrication performance of slider bearing contacts.

The Effect of Elastic Distortions on Journal Bearing Performance

1967 ◽  
Vol 89 (4) ◽  
pp. 409-415 ◽  
Author(s):  
J. O’Donoghue ◽  
D. K. Brighton ◽  
C. J. K. Hooke
Keyword(s):  
Exact Solution ◽  
Pressure Distribution ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Wide Range ◽  
Constant Viscosity ◽  
Outside Diameter

This paper presents a solution to the problem of hydrodynamic lubrication of journal bearings taking into account the elastic distortions of the shaft and the bearing. The exact solution for determining the elastic deformation for a given pressure distribution around a bearing is given, together with the reiterative procedure adopted to find the pressure distribution which satisfies both the hydrodynamic and elastic requirements of the system. Results are given which have been derived for a material with a Poisson’s ratio of 0.28, but other values such as 0.33 do not incur substantial errors. The results can be applied to a wide range of operating conditions using the nondimensional group of terms suggested in the paper. The bearing is assumed to be infinite in length, and infinite in thickness. The latter assumption is shown to be valid for a particular case where the outside diameter of the bearing shell is 3.5 times the shaft diameter. A further assumption in the calculation is a condition of constant viscosity of the lubricant existing around the bearing.

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