The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

2017 ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Surrogate Model ◽  
Load Capacity ◽  
Computing Time ◽  
Friction Torque ◽  
Fluid Film ◽  
Design Parameters ◽  
Textured Surface ◽  
Textured Surfaces ◽  
Thrust Bearings ◽  
Lubricated Contacts

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. The effects of textured surface on lubricated contacts has been widely investigated over the past twenty years. The property of lubricated contacts has been found to play an important role on the performance of fluid film bearings. According to the previous study, the introduction of dimples on the inner surfaces of parallel thrust bearings can improve the load capacity and reduce the friction. Since the friction loss is mostly converted to thermal energy and then increase the temperature, textured surface is expected to have a positive effect on the thermal property of the thrust bearings. A procedure to find the optimal partially texture geometry, which minimize the temperature inside the bearing film, is presented in this study. A parallel sector-pad thrust bearing is simulated by a 3D computational fluid dynamics model. The stationary surface of the bearing is textured with dimples while the rotor surface is flat. The results of the baseline model have been validated by the experimental data from the literature. The temperature and pressure distribution on the bearing pad are presented. In this study, two types of dimples, including rectangular and elliptical, are compared together. A parametric study is conducted to investigate the influence of the texture geometries. In this study, the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extend and circumferential extend are selected as design parameters. A surrogate model is used to reduce the computing time of CFD analysis. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Surrogate Model ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Three Dimensional ◽  
Major Axis ◽  
Friction Torque ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Lubricated Contacts ◽  
Radial Extent

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. A procedure to find the optimal partially textured thrust bearing configuration is presented in this study. A parallel sector-pad thrust bearing is simulated by a three-dimensional (3D) computational fluid dynamics (CFD) model. The stationary surface of the bearing is textured with dimples, while the rotor surface is flat. The results of the baseline model are validated by experimental data. In this study, we compare rectangular and elliptical dimples by investigating design parameters, such as major the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extent, circumferential extent are selected as design parameters. A parametric study is conducted to investigate the influence of the texture geometries and a surrogate model is created. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The results show that the optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

A Comparison Study on the Performance of Four Types of Oil Lubricated Hydrodynamic Thrust Bearings for Hard Disk Spindles

1999 ◽  
Vol 121 (1) ◽  
pp. 114-120 ◽  
Author(s):  
Jiasheng Zhu ◽  
Kyosuke Ono
Keyword(s):  
Load Capacity ◽  
Dynamic Performance ◽  
Hard Disk ◽  
Friction Torque ◽  
The Other ◽  
Design Parameters ◽  
Axial Stiffness ◽  
Comparison Study ◽  
Thrust Bearings ◽  
Optimal Values

In this paper, the static and dynamic performance of herringbone, step-pocket, taper-pocket, and taper-flat thrust bearings were numerically analyzed. Optimal values for the design parameters of each type of bearing were analyzed in terms of both maximum axial stiffness (kzz) and maximum ratio of axial stiffness to friction torque (kzz/T) and bearing performance for both cases was calculated. The optimal performance characteristics of these bearings were compared in terms of application to hard disk spindles. Step-pocket and taper-pocket thrust bearings are superior to herringbone and taper-flat thrust bearings with respect to both the maximum kkk and the maximum kzz/T conditions. It was found that the dams of thrust bearings with pockets play an important part in improving the hearing performance. It was made clear that the taper-pocket and the taper-flat thrust bearings have a much larger load capacity than the other two types of thrust bearings in the proximity of zero clearance.

scholarly journals Semi Salix Leaf Textured Gas Mechanical Face Seal with Enhanced Opening Performance

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7522
Author(s):  
Linqing Bai ◽  
Pengcheng Zhang ◽  
Zulfiqar Ahmad Khan
Keyword(s):  
Friction Torque ◽  
Contact Friction ◽  
Textured Surface ◽  
Face Seal ◽  
Textured Surfaces ◽  
Positive Effects ◽  
Mechanical Face Seal ◽  
Gas Face Seal ◽  
Hydrodynamic Effects ◽  
The Impact

Seal performance of a novel gas mechanical face seal with semi salix leaf textures was introduced and theoretically investigated with the purpose of enhancing hydrostatic and hydrodynamic opening performance. First, a theoretical model of a laser surface textured gas mechanical face seal with semi salix leaf textures was developed. Second, the impact of operating and texturing parameters on open force, leakage, and friction torque was numerically investigated and has been discussed based on gas lubrication theory. Numerical results demonstrate that the semi salix leaf textured gas face seal has larger hydrostatic and hydrodynamic effects than the semi ellipse textured seal because of the effect of the inlet groove. All semi salix leaf textured surfaces had better open performance than the semi ellipse textured surface, which means that the inlet groove plays an important role in improving open performance and consequently decreasing contact friction during the start-up stage. Texturing parameters also influenced the seal performance of thee semi salix leaf textured gas face seal. When the inclination angle was 50°, the radial proportion of the inlet groove was 0.8, the dimple number was 9, and the open force resulted in the maximum value. This research has demonstrated the positive effects of the applications of a semi salix leaf textured gas mechanical face seal that combines the excellent hydrostatic and hydrodynamic effects of groove texture and the excellent wear resistance of microporous textures.

An Optimum Design Approach for Textured Thrust Bearing With Elliptical-Shape Dimples Using Computational Fluid Dynamics and Design of Experiments Including Cavitation

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Design Of Experiments ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Friction Torque ◽  
Load Force ◽  
Optimization Approach ◽  
Thrust Bearings ◽  
Design Variables

Textured thrust bearings are capable of providing higher load capacity and lower friction torque compared to nontextured bearings. However, most previous optimization efforts for texturing geometry were focused on rectangular dimples and employed Reynolds equation. Limited studies have been done to investigate the effects of partially textured thrust bearings with elliptical dimples. This study proposes a new optimization approach to find the optimal partially texture geometry with elliptical dimples, which maximize the loading capacity and minimize the friction torque. In this study, a 3D computational fluid dynamics (CFD) model for a parallel sector-pad thrust bearing is built using ANSYS cfx. Mass conserving cavitation model is used to simulate the cavitation regions. Energy equation for Newtonian flow is also solved. The results of the model are validated by the experimental data from the literature. Based on this model, the flow pattern and pressure distribution inside the dimples are analyzed. The geometry of elliptical dimple is parameterized and analyzed using design of experiments (DOE). The selected geometry parameters include the length of major and minor axes, dimple depth, radial and circumferential space between two dimples, and the radial and circumferential extend. A multi-objective optimization scheme is used to find the optimal texture structure with the load force and friction torque set as objective functions. The results show that the shape of dimples has a crucial effect on the performance of the textured thrust bearings. Searching the design space for a proper combination among the design variables satisfying the constraints has the advantage of capturing the codependence among design variables and leads to a surface patterning of the bearing, which showed a 42.7% improvement on the load capacity.

Surface Texturing Effect, Characterization and Optimization for Boundary and Mixed Lubrication

2011 ◽  
Author(s):  
B. Podgornik ◽  
M. Sedlacˇek
Keyword(s):  
Surface Topography ◽  
Research Work ◽  
Surface Texturing ◽  
Considerable Change ◽  
Mixed Lubrication ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Tribological Behaviour ◽  
Cavity Depth ◽  
Lubricated Contacts

Under boundary and mixed lubrication surface roughness and topography have significant influence on the tribological behaviour of contact surfaces, where even a small change in surface topography can lead to a considerable change in tribological behaviour. In recent years an effort for better controlling friction and wear has been focused also on the surface topography modification, especially on surface texturing. The aim of the present research work was to investigate the possibility of using roughness parameters kurtosis and skewness as design parameters for optimizing texturing pattern in boundary and mixed lubricated contacts. Results of the investigation performed on groove and dimple textured surfaces under low load low sliding speed conditions confirm correlation between kurtosis and skewness parameters and coefficient of friction. For textured surfaces increase in kurtosis and more negative skewness, obtained by reducing cavity size, increasing cavity depth and decreasing texturing density were found to yield lower friction. Furthermore, kurtosis and skewness were recognized as suitable parameters for textured surfaces optimization. Through virtual texturing effect of different texturing parameters on kurtosis and skewness parameters can be identified and then optimized to result in reduced friction under boundary and mixed lubrication.

An Investigation of Design Parameters Influencing the Fluid Film Behavior in Scaled Cylinder Block/Valve Plate Interface

2016 ◽  
Author(s):  
L. Shang ◽  
M. Ivantysynova
Keyword(s):  
Energy Dissipation ◽  
Computational Study ◽  
Interaction Model ◽  
Friction Torque ◽  
Valve Plate ◽  
Fluid Film ◽  
Cylinder Block ◽  
Design Parameters ◽  
Plate Interface ◽  
Piston Cylinder

The efficiency of an axial piston pump or motor is dominated by the volumetric and torque losses of the three main lubricating interfaces (piston/cylinder, cylinder block/valve plate, and slipper/swash plate). The research study in this paper only focuses on the cylinder block/valve plate interface. The goal of this research is to investigate a novel approach for scaling the cylinder block/valve plate interface to have the same percentage of volumetric and torque losses of the baseline interface. To achieve this research goal, many design parameters influencing the performance of the interface are investigated. An in-house developed fluid structure and thermal interaction model was used to analyze the cylinder block/valve plate interface including the resulting parts temperature, the parts elastic deformation due to pressure and thermal load, the fluid film properties and resulting energy dissipation, friction torque, and leakage of cylinder block/valve plate interfaces. This model is utilized to simulate the cylinder block/valve plate interface performance of different sizes of the displacement units. In this paper, the displacement volume of the biggest unit is sixty-four times larger than the smallest unit. The computational study reveals the design parameters influencing the elastic deformations of the solid parts and the energy dissipation and stability of the fluid film in cylinder block/valve plate interface of different sizes. Based on these investigations, a novel scaling approach to scale the cylinder block/valve plate interface is discussed.

Centrifugal Effects in Misaligned Hydrostatic Thrust Bearings

1983 ◽  
Vol 105 (4) ◽  
pp. 621-624 ◽  
Author(s):  
Z. S. Safar
Keyword(s):  
Flow Rate ◽  
Load Capacity ◽  
Friction Torque ◽  
Centrifugal Forces ◽  
Thrust Bearings ◽  
Lubricant Flow

An analysis is conducted and solutions are provided for the effect of centrifugal forces on hydrostatic misaligned thrust bearings. The results show that centrifugal forces reduce considerably the load capacity, the friction torque and increase the lubricant flow rate. It is found that the effect of centrifugal forces is decreased as tilting of the bearing is increased.

Design and Performance Prediction of Hybrid Air Foil Thrust Bearings

2010 ◽  
Vol 133 (4) ◽  
Author(s):  
Donghyun Lee ◽  
Daejong Kim
Keyword(s):  
Load Capacity ◽  
Experimental Studies ◽  
Leading Edge ◽  
Friction Torque ◽  
Operating Conditions ◽  
Design Parameters ◽  
Foil Bearings ◽  
Supply Pressure ◽  
Low Speeds ◽  
Land Region

Air foil bearings (AFBs) have been recognized as the most promising for oil-free turbomachinery. However, the applications of AFBs to the relatively large turbomachinery have many technical challenges due to limited load capacity and wear during start/stops. A hybrid air foil bearing (HAFB), which combines the benefits of AFB and hydrostatic air bearing, was introduced earlier by the authors, and the experimental studies showed much larger load capacity at low speeds and much lesser friction torque during start/stop than hydrodynamic counterpart. The benefit of HAFB was recognized through the experimental studies, and the concept of hybrid operation was further developed to thrust air foil bearings. This paper presents novel design features of the hybrid air foil thrust bearing (HAFTB) with radially arranged bump foils and preformed Rayleigh step contour, and presents simulated static and dynamic characteristics of the HAFTB. A 2D thin plate equation in cylindrical coordinate was solved with the finite difference method for the prediction of the top foil deflection. Parametric studies were performed to evaluate the effect of various design parameters on the static and dynamic performances of HAFTB. At low speeds, a design with orifice located at the center of land region showed the highest load capacity, while a design with orifice located near the leading edge of land region showed the highest load capacity at high speeds. Direct and coupled bearing coefficients were also calculated for various operating conditions. The direct stiffness increases with supply pressure but the direct damping decreases with supply pressure. In addition, typical hardening effect of gas film accompanying increase of stiffness and decrease of damping was predicted in high frequency excitations.

scholarly journals Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves

Lubricants ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Eckhard Schüler ◽  
Olaf Berner
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Fluid Film ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Tilting Pad ◽  
Bearing Load ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.

scholarly journals Fast laser surface texturing of spherical samples to improve the frictional performance of elasto-hydrodynamic lubricated contacts

Friction ◽  
2021 ◽  
Author(s):  
G. Boidi ◽  
P. G. Grützmacher ◽  
A. Kadiric ◽  
F. J. Profito ◽  
I. F. Machado ◽  
...  
Keyword(s):  
Surface Texturing ◽  
Hydrodynamic Pressure ◽  
Friction Reduction ◽  
Laser Surface Texturing ◽  
Textured Surfaces ◽  
Engineering Applications ◽  
Lubricated Contacts ◽  
Fluid Uptake ◽  
Direct Laser ◽  
Frictional Performance

AbstractTextured surfaces offer the potential to promote friction and wear reduction by increasing the hydrodynamic pressure, fluid uptake, or acting as oil or debris reservoirs. However, texturing techniques often require additional manufacturing steps and costs, thus frequently being not economically feasible for real engineering applications. This experimental study aims at applying a fast laser texturing technique on curved surfaces for obtaining superior tribological performances. A femtosecond pulsed laser (Ti:Sapphire) and direct laser interference patterning (with a solid-state Nd:YAG laser) were used for manufacturing dimple and groove patterns on curved steel surfaces (ball samples). Tribological tests were carried out under elasto-hydrodynamic lubricated contact conditions varying slide-roll ratio using a ball-on-disk configuration. Furthermore, a specific interferometry technique for rough surfaces was used to measure the film thickness of smooth and textured surfaces. Smooth steel samples were used to obtain data for the reference surface. The results showed that dimples promoted friction reduction (up to 20%) compared to the reference smooth specimens, whereas grooves generally caused less beneficial or detrimental effects. In addition, dimples promoted the formation of full film lubrication conditions at lower speeds. This study demonstrates how fast texturing techniques could potentially be used for improving the tribological performance of bearings as well as other mechanical components utilised in several engineering applications.

Sign in / Sign up

Export Citation Format

Share Document