Texturing Effects in Plane-Inclined Slider Bearings

2007 ◽  
Author(s):  
Mihai B. Dobrica ◽  
Michel Fillon ◽  
Mircea D. Pascovici ◽  
Traian Cicone
Keyword(s):  
Load Capacity ◽  
Surface Texturing ◽  
Cylinder Liner ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Slider Bearings ◽  
Parametric Studies ◽  
Friction Reducing ◽  
Performance Gains

Surface texturing has been shown to have friction reducing / load capacity increasing effects in parallel sliders, as well as in cylinder-liner contacts and in hydrodynamic seals. However, if texture is to be regarded as the sole mean of hydrodynamic lift in parallel sliders, or as a way of improving hydrodynamic performance in slider, thrust and journal bearings, several issues have to be addressed, such as optimal texturing parameters and corresponding performance gains. This paper deals with these issues in the case of a plane inclined textured slider. Parametric studies are conducted to determine optimal texturing extents, dimple depth and texturing density, as well as the influence of the operating conditions on these optimal texturing parameters.

scholarly journals A Numerical Model to Study the Role of Surface Textures at Top Dead Center Reversal in the Piston Ring to Cylinder Liner Contact

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
N. Morris ◽  
R. Rahmani ◽  
H. Rahnejat ◽  
P. D. King ◽  
S. Howell-Smith
Keyword(s):  
Gas Flow ◽  
Fuel Efficiency ◽  
Surface Texturing ◽  
Engine Performance ◽  
Cylinder Liner ◽  
Operating Conditions ◽  
Ic Engine ◽  
Numerical Predictions ◽  
Combined Solution ◽  
Effect Of Surface

Minimization of parasitic losses in the internal combustion (IC) engine is essential for improved fuel efficiency and reduced emissions. Surface texturing has emerged as a method palliating these losses in instances where thin lubricant films lead to mixed or boundary regimes of lubrication. Such thin films are prevalent in contact of compression ring to cylinder liner at piston motion reversals because of momentary cessation of entraining motion. The paper provides combined solution of Reynolds equation, boundary interactions, and a gas flow model to predict the tribological conditions, particularly at piston reversals. This model is then validated against measurements using a floating liner for determination of in situ friction of an engine under motored condition. Very good agreement is obtained. The validated model is then used to ascertain the effect of surface texturing of the liner surface during reversals. Therefore, the paper is a combined study of numerical predictions and the effect of surface texturing. The predictions show that some marginal gains in engine performance can be expected with laser textured chevron features of shallow depth under certain operating conditions.

Analysis of Noncircular Gas Journal Bearings

1975 ◽  
Vol 97 (4) ◽  
pp. 616-623 ◽  
Author(s):  
O. Pinkus
Keyword(s):  
Reynolds Equation ◽  
Load Capacity ◽  
Full Range ◽  
Maximum Load ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Significant Advance ◽  
Arbitrary Direction ◽  
Isothermal Conditions ◽  
Load Vector

The compressible Reynolds Equation under isothermal conditions was solved for finite elliptical and 3-lobe bearings with the load vector acting in any arbitrary direction over the full range of 360 deg. Envelopes of minimum and maximum eccentricity for a given set of operating conditions are provided, the first to yield maximum load capacity, and the second to assist stability by a choice of the highest possible ε. Some values of the spring and damping forces are also given and it is shown that in comparison with conventional bearings, the non-circular designs offer a significant advance in stiffness, particularly for low ε, when instability is most often encountered.

Feasibility of Gas-Expanded Lubricants for Increased Energy Efficiency in Tilting-Pad Journal Bearings

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Andres Clarens ◽  
Amir Younan ◽  
Shibo Wang ◽  
Paul Allaire
Keyword(s):  
Supercritical Co2 ◽  
Power Loss ◽  
Load Capacity ◽  
Reducing Power ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Eccentricity Ratio ◽  
Power Losses ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

Lubricants are necessary in tilting-pad journal bearings to ensure separation between solid surfaces and to dissipate heat. They are also responsible for much of the undesirable power losses that can occur through a bearing. Here, a novel method to reduce power losses in tilting-pad journal bearings is proposed in which the conventional lubricant is substituted by a binary mixture of synthetic lubricant and dissolved CO2. These gas-expanded lubricants (GELs) would be delivered to a reinforced bearing housing capable of withstanding modest pressures less than 10 MPa. For bearings subject to loads that are both variable and predictable, GELs could be used to adjust lubricant properties in real time. High-pressure lubricants, mostly gases, have already been explored in tilting-pad journal bearings as a means to accommodate higher shaft speeds while reducing power losses and eliminating the potential for thermal degradation of the lubricant. These gas-lubricated bearings have intrinsic limitations in terms of bearing size and load capacity. The proposed system would combine the loading capabilities of conventional lubricated bearings with the efficiency of gas-lubricated bearings. The liquid or supercritical CO2 serves as a low-viscosity and completely miscible additive to the lubricant that can be easily removed by purging the gas after releasing the pressure. In this way, the lubricant can be fully recycled, as in conventional systems, while controlling the lubricant properties dynamically by adding liquid or supercritical CO2. Lubricant properties of interest, such as viscosity, can be easily tuned by controlling the pressure inside the bearing housing. Experimental measurements of viscosity for mixtures of polyalkylene glycol (PAG)+CO2 at various compositions demonstrate that significant reductions in mixture viscosity can be achieved with relatively small additions of CO2. The measured parameters are used in a thermoelastohydrodynamic model of tilting-pad journal bearing performance to evaluate the bearing response to GELs. Model estimates of power loss, eccentricity ratio, and pad temperature suggest that bearings would respond quite favorably over a range of speed and preload conditions. Calculated power loss reductions of 20% are observed when compared with both a reference petroleum lubricant and PAG without CO2. Pad temperature is also maintained without significant increases in eccentricity ratio. Both power loss and pad temperature are directly correlated with PAG-CO2 composition, suggesting that these mixtures could be used as “smart” lubricants responsive to system operating conditions.

Mass Conserving Elastohydrodynamic Piston Lubrication Model With Incorporated Crown Lands

2007 ◽  
Author(s):  
Mustafa Duyar
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Cylinder Liner ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Piston Skirt ◽  
Piston Crown ◽  
Parametric Studies ◽  
Volume Method ◽  
Crown Lands

This paper describes a comprehensive model of Elastohydrodynamic piston lubrication, incorporated the crown lands into solution domain to characterize the effect of crown-liner interactions on piston motion. Elastohydrodynamic Lubrication (EHL) analysis of a piston skirt-liner conjunction is in general a useful methodology for design analysis of pistons. The diameters of piston crown lands are much less than those of skirt and liner for typical piston designs. Therefore crown lands normally do not interact with liner under usual operating conditions and hence most of the researchers exclude crown lands from the EHL analysis and mainly focus on piston skirt. However, under some of the engine operating conditions piston crown lands play important role in the secondary dynamics and tribology aspects of pistons. During the thermodynamic cycle when piston is hot and cylinder liner is relatively colder, piston thermal expansion leads to crown-liner interaction, which necessitates EHL, asperity contact and wear considerations of piston crown along with piston skirt. The simulation methodology for piston EHL analysis uses a mass-conserving algorithm for the finite volume method solution of Reynolds equation, which is coupled to elasticity relations and Greenwood-Tripp asperity contact model. Elrod’s mass conserving algorithm enables to model and analyze partially lubricated piston-liner interface by the input of oil supply and moreover rigorously handles cavitated zones, and takes into account piston ring grooves, piston cut-outs and unlubricated areas due to piston geometry. Results are presented from parametric studies that show comparisons between the analyses of the models with piston skirt lubrication only and piston lubrication, which incorporates the crown lands to the EHL domain.

THE EFFECT OF HELICAL GROOVE PRESENCE ON THE TRIBOLOGICAL PERFORMANCE OF JOURNAL BEARINGS

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 131-138
Author(s):  
Jarosław SĘP ◽  
Leszek TOMCZEWSKI ◽  
Lidia GAŁDA
Keyword(s):  
Load Capacity ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Equation System ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Static Characteristics ◽  
Hydrodynamic Bearings ◽  
Oil Flow ◽  
Helical Groove

The hydrodynamic bearings could suffer critical damages operating in contaminated environments that cause machine breakdown. In such hard operating conditions, hydrodynamic bearings with grooved journals are less sensitive to damage compared to plain bearings. The wear resistance of the grooved journal bearings is several times greater than that of smooth journal bearings. Contaminants existing in the oil film are moved out from the bearing clearance by the groove created on the journal surface. The presence, shape, and geometry of the groove strongly influence the bearings performance. The aim of this article is to study the selected static characteristics of bearings consisting of a journal with the helical groove on its surface. The static characteristics were determined based on the flow simulation in the oil clearance. A three-dimensional, adiabatic model of the oil flow was assumed. The oil flow was described with the Navier-Stokes continuity and energy equations. The equation system was solved by the finite volume method. The numerical model of the flow was verified experimentally on a test stand. It has been established that the grooved journal application leads to a decrease of load capacity in whole range of eccentricity and for all examined clearances. The oil flow rate increase was mainly observed due to spiral groove presence on the shaft.

Static and dynamic characteristics and stability analysis of high-speed water-lubricated hydrodynamic journal bearings

2021 ◽  
pp. 135065012110270
Author(s):  
Bo Xu ◽  
Hun Guo ◽  
Xiaofeng Wu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Load Capacity ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Inertia Effect ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Stiffness And Damping

The purpose of this paper is to analyze the influence of turbulent, inertia, and misaligned effects on the static and dynamic characteristics and stability of high-speed water-lubricated hydrodynamic journal bearings. Based on the Navier–Stokes equation, the mixing-length theory, and the essential assumption that the velocity profile is not strongly affected by inertia force, the fluid lubrication model with turbulent, inertia, and misaligned effects is established, and then the stability analysis of bearings is carried out based on the equation of motion with four degrees of freedom. The model is solved by the finite difference method and the numerical results are compared under different operating conditions. The results show that the turbulent effect greatly increases the load capacity, power consumption, stiffness and damping coefficients, and stability of bearings, and the inertia effect significantly increases the volume flow rate of bearings, and the misaligned effect increases the load capacity, stiffness and damping coefficients, and stability of bearings. In high rotary speed and moderate eccentricity ratios, the influence of the inertia effect on the load capacity, stiffness coefficients, and stability cannot be neglected.

A Method of Controlling the Shaft Misalignment in a Gear Testing Machine by “Prestressed” Externally Pressurized Journal Bearings

1975 ◽  
Vol 97 (3) ◽  
pp. 814-819 ◽  
Author(s):  
C. Cusano ◽  
A. Mirarefi ◽  
E. Radzimovsky
Keyword(s):  
Load Capacity ◽  
Analytical Data ◽  
Testing Machine ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Lubricant Flow ◽  
Shaft Misalignment ◽  
Four Square ◽  
Loaded Side ◽  
Bearing System

“Prestressed” externally pressurized journal bearings employing capillary restrictors as compensating elements are installed on a four-square gear testing machine for the purpose of investigating the frictional phenomena in gearing. The bearings are designed so that the position of the shafts can be aligned with the geometric axes of the bearings by operating the bearing system at zero, positive, or negative eccentricities. These operating conditions are made possible by employing capillary restrictors whose conductance is larger on the loaded side of the bearings than on the unloaded side. Analytical data are presented which give the load capacity, lubricant flow rate requirements, and stiffness of the bearing for given geometry of the bearing and capillary restrictors and for a given eccentricity ratio. In addition, analytical and experimental data are presented from which, for a given load, the required supply pressure can be selected so that the bearing system, on the gear testing machine, operates at zero eccentricity.

Evaluation of textured journal bearings under dynamic operating conditions in rotating machinery

2019 ◽  
Vol 234 (6) ◽  
pp. 842-857 ◽  
Author(s):  
Leandro Ito Ramos ◽  
Douglas Jhon Ramos ◽  
Gregory Bregion Daniel
Keyword(s):  
Surface Texturing ◽  
Load Condition ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
Operating Conditions ◽  
Computational Time ◽  
Energetic Efficiency ◽  
Rotating Machines ◽  
Viscous Forces ◽  
Equivalent Static Load

In order to obtain rotating machinery with improved energy efficiency, the approach of surface texturing journal bearings has been adopted to reduce the viscous dissipation in the lubricant. A possible reduction in shear viscous forces in the bearings of rotating machines could reduce the amount of heat released along its operation, resulting in a lower operating temperature that tends to improve journal bearings performance and the machine’s energetic efficiency. Thus, this work aims to investigate the texturing of journal bearings under dynamic loading conditions, considering the application in rotating systems. For this, computational simulations are performed through a rotating system model constructed by means of the finite element method in which the hydrodynamic journal bearings that support the rotor are modeled by Reynolds’ equation using the finite volume method and the full multigrid technique. The numerical results show that textured journal bearings can be applied to rotating machines, providing reductions in shear viscous forces. However, the magnitude of this reduction should be carefully evaluated, as the Reynolds cavitation model was applied to ensure a lower computational spent time and thus enable the simulations involved in this study. The novelty of this study is related to determining the appropriate distributions and geometric parameters of the textures for the journal bearing under dynamic load condition considering its equivalent static load condition what tends to drastically reduce computational time to perform this procedure, representing an important alternative for industrial application.

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.

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.

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