Low Friction and High Load Support Capacity of Slider Bearing With a Mixed Slip Surface

2006 ◽  
Vol 128 (4) ◽  
pp. 904-907 ◽  
Author(s):  
C. W. Wu ◽  
G. J. Ma ◽  
P. Zhou ◽  
C. D. Wu
Keyword(s):  
Slip Surface ◽  
Hydrodynamic Pressure ◽  
Solid Surfaces ◽  
Fluid Film ◽  
Necessary Condition ◽  
Friction Drag ◽  
Slider Bearing ◽  
Boundary Slip ◽  
Fluid Load ◽  
Viscous Fluid Film

The classical Reynolds theory reveals that a converging gap is the first necessary condition to generate a hydrodynamic pressure in a viscous fluid film confined between two solid surfaces with a relative sliding/rolling motion. For hundreds of years, the classical lubrication mechanics has been based on the frame of the Reynolds theory with no slip assumption. Recent studies show that a large boundary slip occurs on an ultrahydrophobic surface, which results in a very small friction drag. Unfortunately, such a slip surface also produces a small hydrodynamic pressure in a fluid film between two solid surfaces. This paper studies the lubrication behavior of infinite width slider bearings involving a mixed slip surface (MSS). The results of the study indicate that any geometrical wedges (gaps), i.e., a convergent wedge, a parallel gap, and even a divergent wedge, can generate hydrodynamic pressure in an infinite slider bearing with a mixed slip surface. It is found that with an MSS, the maximum fluid load support capacity occurs at a slightly divergent wedge (roughly parallel sliding gap) for an infinite width slider bearing, but not at a converging gap as what the classical Reynolds theory predicts. Surface optimization of a parallel sliding gap with a slip surface can double the hydrodynamic load support and reduce the friction drag by half of what the Reynolds theory predicts for an optimal wedge of a traditional slider bearing.

Numerical and Experimental Study on Fabrication of Microstructure Array with Topographical Gradient via Through-Mask EMM

2012 ◽  
Vol 528 ◽  
pp. 254-258 ◽  
Author(s):  
Quan Dai Wang ◽  
Ji Ming Xiao ◽  
Yan Jun Lü
Keyword(s):  
Hydrodynamic Pressure ◽  
Current Density Distribution ◽  
Fluid Film ◽  
Electrochemical Micromachining ◽  
Anode Surface ◽  
Necessary Condition ◽  
Textured Surface ◽  
Confined Fluid ◽  
Fluid Load ◽  
Microstructure Array

To obtain textured surface with low friction and high fluid load support capacity, in this work, based on the basic tenet of fluid film lubrication theory that converging gap is the first necessary condition to generate a hydrodynamic pressure in a confined fluid film, a fabrication method via through-mask electrochemical micromachining (EMM) for microstructure array on metal substrate with topographical gradient in a single micromachining step is investigated. After analyzing the factors that influence the current density distribution on the anode surface in EMM process, three potentially feasible schemes are presented and their fabrication results are predicted through numerical simulation. Combining the simulation results with practical application requirements, the scheme with machining gap gradient is adopted. With the selected fabrication scheme, the experiments are performed and the microstructure array with a feature size of 25μm and a height variance from 12μm to 24μm within 2mm distance has been produced successfully, which is in good agreement with the numerical calculation prediction.

Hydrodynamic Load Support of a Slip Wedge

Tribology ◽  
2006 ◽  
Author(s):  
C. W. Wu ◽  
G. J. Ma
Keyword(s):  
Hydrodynamic Pressure ◽  
Wall Slip ◽  
Surface Friction ◽  
Two Dimensional ◽  
Hydrodynamic Load ◽  
Friction Drag ◽  
Slider Bearing ◽  
Small Surface ◽  
Slip Control ◽  
Control Equation

This paper studies the hydrodynamic load support generated by a slip wedge of a slider bearing. The surface slip property is optimized to obtain a maximum hydrodynamic load support. A multi-linearity method was used to approach the slip control equation of two-dimensional (2-D) wall slip. It is found that the hydrodynamic pressure generated in the slip wedge is greater than that of the traditional geometrical convergent-wedge. Even though the geometrical gap is a parallel or divergent sliding gap, the slip wedge still gives rise to a very big hydrodynamic pressure. The optimized slip wedge gives rise to a maximum hydrodynamic load support as large as 2.5 times of what the Classical Reynolds theory predicts for the geometrical convergent-wedge. Wall slip usually gives a small surface friction drag.

Investigation of slip/no-slip surface for two-dimensional large tilting pad thrust bearing

2017 ◽  
Vol 69 (6) ◽  
pp. 995-1004 ◽  
Author(s):  
Zhixiang Song ◽  
Fei Guo ◽  
Ying Liu ◽  
Songtao Hu ◽  
Xiangfeng Liu ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Slip Surface ◽  
Load Capacity ◽  
Slip Condition ◽  
Optimized Design ◽  
Two Dimensional ◽  
Boundary Slip ◽  
Content Type ◽  
Tilting Pad ◽  
Turbulence Effect

Purpose This paper aims to present the slip/no-slip design in two-dimensional water-lubricated tilting pad thrust bearings (TPTBs) considering the turbulence effect and shifting of pressure centers. Design/methodology/approach A numerical model is established to analyze the slip condition and the effect of turbulence according to a Reynolds number defined in terms of the slip condition. Simulations are carried out for eccentrically and centrally pivoted bearings and the influence of different slip parameters is discussed. Findings A considerable enhancement in load capacity, as well as a reduction in friction, can be achieved by heterogeneous slip/no-slip surface designs for lubricated sliding contacts, especially for near parallel pad configurations. The optimized design largely depends on the pivot position. The load capacity increases by 174 per cent for eccentrically pivoted bearings and 159 per cent for centrally pivoted bearings for a suitable design. When slip zone locates at the middle of the radial direction or close to the inner edge, the performance of the TPTB is better. Research limitations/implications The simplification of slip effect on the turbulence (definition of Reynolds number) can only describe the trend of the increasing turbulence due to slip condition. The accurate turbulence expression considering the boundary slip needs further explorations. Originality/value The shifting of pressure center due to the slip/no-slip design for TPTBs is investigated in this study. The turbulence effect and influence of slip parameters is discussed for large water-lubricated bearings.

scholarly journals Comparison of the Influences of Surface Texture and Boundary Slip on Tribological Performances

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Qiyin Lin ◽  
Baotong Li
Keyword(s):  
Surface Texture ◽  
Slip Velocity ◽  
Structure Parameters ◽  
Textured Surfaces ◽  
Slider Bearing ◽  
Boundary Slip ◽  
Surface Textures ◽  
Slip Surfaces ◽  
Texture Structure ◽  
The Relationship

Close attentions have been widely paid to the engineering textured and slip surfaces for improving bearing tribological performances. Comparison studies on the tribological characteristics of slip and textured surfaces are carried out in this work. The analysis results point out that the influences of surface texture and boundary slip on tribological performances of slider bearing are strongly similar. For the determinate surface textures, there is one and only value of slip velocity to make the tribological performances of textured and slip surfaces in agreement. The corresponding relation between the slip velocity and the texture structure parameters is also obtained, and the size of slip velocity is directly related to the texture geometry parameters including its position parameters. This study will help us to further understand the relationship between boundary slip and surface texture and also the slip phenomenon.

Thermohydrodynamic Modeling of a Tapered-Land Thrust Bearing With Validation Against Experimental Data

2021 ◽  
Author(s):  
Seckin Gokaltun
Keyword(s):  
Heat Transfer ◽  
Transfer Problem ◽  
Load Capacity ◽  
Solid Surfaces ◽  
Fluid Film ◽  
Transfer Model ◽  
Analysis Model ◽  
Load Range ◽  
Benchmark Data ◽  
Computational Fluid Dynamics Cfd

Abstract In this work, a computational fluid-film bearing analysis model has been utilized in order to investigate the conjugate heat transfer problem for a tapered-land bearing using computational fluid dynamics (CFD) analysis. The academic model is based on the 2D Reynolds equation for the pressure distribution in the film the 3D energy equation is solved for the the bearing pad and the fluid film; therefore, the lubricant properties such as viscosity and density could be made temperature-dependent. The runner is modeled using a 2D axisymmetric mesh. The current analysis excludes the mechanical or thermal deformations of the bearing and the runner since it was observed that the results for output quantities such as film temperature, film pressure, torque and load capacity were within reasonable agreement with the benchmark data obtained from the experiments for the majority of the speed and load cases studied. Comparisons of modeling results against the benchmark data was obtained for cases ranging from 2000 rpm to 10,000 rpm at loads varying from 1000 N to 8000 N. The importance of proper boundary conditions used in the heat transfer model is emphasized as well as the coupling of heat transfer between the film and the solid surfaces of collar and the bearing is described. The results obtained here yielded that a thermohydrodynamic (THD) model that includes the energy transfer into the structures surrounding the fluid film is sufficient enough to predict the performance of a tapered-land bearing at a wide speed and load range in the case where the runner is thick enough that the effect of deformations on the results can be ignored.

Stability of a thin viscous fluid film flowing down a rotating non-uniformly heated inclined plane

2010 ◽  
Vol 216 (1-4) ◽  
pp. 225-242 ◽  
Author(s):  
Asim Mukhopadhyay ◽  
Anandamoy Mukhopadhyay
Keyword(s):  
Viscous Fluid ◽  
Fluid Film ◽  
Inclined Plane ◽  
Viscous Fluid Film

scholarly journals A comparison of porous structures on the performance of slider bearing with surface roughness in micropolar fluid film lubrication

2019 ◽  
Vol 23 (3 Part B) ◽  
pp. 1813-1824 ◽  
Author(s):  
Pentyala Rao ◽  
Birendra Murmu ◽  
Santosh Agarwal
Keyword(s):  
Surface Roughness ◽  
Micropolar Fluid ◽  
Fluid Film ◽  
Porous Structures ◽  
Slider Bearing ◽  
Sphere Model ◽  
Load Carrying ◽  
Improved Performance ◽  
Film Lubrication ◽  
Fluid Film Lubrication

This paper presents the theoretical analysis of comparison of porous structures on the performance of a slider bearing with surface roughness in micropolar fluid film lubrication. The globular sphere model and Irmay?s capillary fissures model have been subject to investigations. The general Reynolds equation which incorporates randomized roughness structure with Stokes micropolar fluid is solved with suitable boundary conditions to get the pressure distribution, which is then used to obtain the load carrying capacity. The graphical representations suggest that the globular sphere model scores over the Irmay?s capillary fissures model for an overall improved performance. The numerical computations of the results show that, the act of the porous structures on the performance of a slider bearing is improved for the micropolar lubricants as compared to the corresponding Newtonian lubricants.

Investigation of Lubrication Characteristics for a Soft Contact Lens

2019 ◽  
Vol 823 ◽  
pp. 105-109
Author(s):  
Hung Jung Tsai ◽  
Jeng Haur Horng ◽  
Chung Ming Tan
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Hydrodynamic Lubrication ◽  
Tear Film ◽  
Hydrodynamic Pressure ◽  
Slider Bearing ◽  
Soft Contact ◽  
Soft Contact Lens ◽  
Lubrication Characteristics

It is popular to wear the contact lens nowadays. Also, the output value of the contact lens is estimated more than 4 billion NT dollar every year. Because the phenomena of the contact lenses are very complicated, the relevant mechanisms are not well understood. Thus, the security of contact lens needs to be further investigated. In the lubricated mechanism of the contact lens, there is a layer of tear between the contact lens and cornea. The contact lens’ behavior is akin to that of a slider bearing. The lens represents the slider, the eye plays the role of the stationary pad, and the tear film is the lubricant. Hence, hydrodynamics and contact mechanisms of a contact lens are quite a fascinating subject that is relevant to the science of tribology. In the paper, the lubrication mechanisms include the partial hydrodynamic lubrication (contact lens roughness), contact mechanics and Newtonian fluid mechanics have been established. The parameters of roughness, flow factor, tear film geometry, and hydrodynamic pressure distribution are discussed. The developed technology increases the safety of contact lens.

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