Relationship Between Temperature Distribution in EHL Film and Dimple Formation

2005 ◽  
Vol 127 (3) ◽  
pp. 658-665 ◽  
Author(s):  
Kazuyuki Yagi ◽  
Keiji Kyogoku ◽  
Tsunamitsu Nakahara
Keyword(s):  
Phase Transition ◽  
Experimental Study ◽  
Temperature Distribution ◽  
Elastohydrodynamic Lubrication ◽  
Infrared Emission ◽  
Maximum Temperature ◽  
Oil Film ◽  
Sliding Direction ◽  
Oil Flow ◽  
Ball Surface

This paper describes an experimental study on dimple formation under elastohydrodynamic lubrication (EHL) conditions. The oil film thickness between a ball surface and a glass disk was measured using optical interferometry, and the temperatures of both the surfaces and of the oil film averaged across it were measured using an infrared emission technique. It was found that the temperature profile across the oil film varies abruptly along the sliding direction, and the Couette flow decreases due to the viscosity wedge action as the oil flow is close to the dimple zone. The maximum temperature rise in the dimple zone sometimes reached over 400 K, thus, the phase transition of the oil from liquid to glass may not occur.

Relationship Between Temperature Distribution in EHL Film and Dimple Formation

2004 ◽  
Author(s):  
Kazuyuki Yagi ◽  
Keiji Kyogoku ◽  
Tsunamitsu Nakahara
Keyword(s):  
Phase Transition ◽  
Experimental Study ◽  
Temperature Distribution ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Infrared Emission ◽  
Maximum Temperature ◽  
Oil Film ◽  
Oil Flow ◽  
Ball Surface

This paper describes an experimental study on dimple formations under elastohydrodynamic lubrication (EHL) conditions. The oil film thickness between a ball surface and a sapphire disk was measured using optical interferometry and the temperatures of both the surfaces and of the oil film averaged across it were measured by an improved infrared emission technique. It was found that temperature profile across the oil film varies abruptly along the direction of the oil film thickness and the Couette flow decreases due to the viscosity wedge action as the oil flow is close to the dimple zone. The maximum temperature rise in the dimple zone sometimes reached above 400 K and thus the phase transition of the oil from liquid to glass may not occur.

scholarly journals The effect of oil feeding type and oil grade on the oil film bearing capacity

2021 ◽  
Vol 23 (2) ◽  
pp. 381-386
Author(s):  
Aleksander Mazurkow ◽  
Waldemar Witkowski ◽  
Adam Kalina ◽  
Bartłomiej Wierzba ◽  
Mariusz Oleksy
Keyword(s):  
Bearing Capacity ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
Static Characteristics ◽  
Oil Film ◽  
Feeding Type ◽  
Oil Flow ◽  
Minimum Height ◽  
Face Side

Two types of hydrodynamically lubricated plain journal bearings were subject to examination differing in the method used to feed them with oil. The first type was fed from a lubrication pocket and the second from the bearing face side. Mathematical models were developed with two-way oil flow allowing to determine the oil film bearing capacity, the maximum pressure, the maximum temperature, and the film oil minimum height for given position of journal relative to solid bush. Static characteristics were developed used in the further course of the study to compare operating parameters of the considered types of bearings. Another issue considered in the paper is the effect of oil VG grade on bearing performance with conditions of oil feeding taken into account and results of the research presented.

Effects of longitudinal roughness on fluid temperature in point elastohydrodynamic lubrication contacts

2007 ◽  
Vol 221 (7) ◽  
pp. 793-799 ◽  
Author(s):  
H Nishikawa ◽  
K Ueda ◽  
M Kaneta ◽  
J Wang ◽  
P Yang
Keyword(s):  
Temperature Distribution ◽  
Newtonian Fluid ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Shear Thinning ◽  
Fluid Temperature ◽  
Oil Film ◽  
Flow Models ◽  
Shear Thinning Fluids ◽  
Significant Difference

The effects of longitudinal surface roughness on the oil film temperature are studied numerically based on Eyring and Newtonian fluid flow models under point contact rolling and sliding elastohydrodynamic lubrication (EHL) conditions. There is a significant difference in oil film temperature distribution between the Eyring or shear thinning fluid and the Newtonian fluid. In shear thinning fluids, the relationship between the oil film temperature distribution and the roughness around the central contact area becomes out-of-phase, i.e. the temperature of oil film is higher at the valley than at the ridge of asperity. Such a phenomenon occurs easily under short wavelength and low amplitude of roughness, and moderate entrainment velocities depending on the slide-roll ratio.

Experimental Study of Elastohydrodynamic Lubrication under Heavy Loaded and Variable Velocity Conditions

2015 ◽  
Vol 713-715 ◽  
pp. 173-177
Author(s):  
Nai Ming Miao
Keyword(s):  
Experimental Study ◽  
Elastohydrodynamic Lubrication ◽  
The Self ◽  
Stepper Motor ◽  
Variable Velocity ◽  
Motor Speed ◽  
Oil Film ◽  
Lubrication Characteristics ◽  
Velocity Mutation ◽  
Motor Velocity

In order to reveal the elastohydrodynamic lubrication characteristics under heavy loaded and variable velocity conditions, We carried out the relevant experiments by the self-developed optical interference EHL experimental device. Improved apparatus substitute screw for the slider-crank, and driven by stepper motor. Velocity mutation experiment carried out to discuss features of the oil film while the stepper motor speed instantly changes from the velocity of 0.23mm/s, 0.38mm/s and 0.52mm/s. It shows that extrusion effect and oil film sag emerge in acceleration instantaneous similar to zero entrainment speed even it is not, and end of oil film has a necking phenomenon distinctly.

Experimental study for performance evaluation of steadily loaded true elliptical and orthogonally displaced non-circular journal bearing profiles

2016 ◽  
Vol 68 (6) ◽  
pp. 702-711 ◽  
Author(s):  
Amit Singla ◽  
Amit Chauhan
Keyword(s):  
Experimental Study ◽  
Thermal Performance ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Positive Pressure ◽  
Film Pressure ◽  
Content Type ◽  
Oil Film ◽  
Oil Film Pressure

Purpose The non-circular journal bearings may be used over circular journal bearings because of their superior thermal stability. The paper aims at experimental study of thermal performance of two different true elliptical and orthogonally displaced non-circular journal bearing profiles. Design/methodology/approach The experiments have been conducted on a specially designed test rig which simultaneously evaluates oil film pressure and temperature along the circumference of non-circular journal bearing. The tests are conducted for the designed true elliptical and orthogonally displaced journal bearing at three different rotational speeds of 2,000, 3,000 and 4,000 rpm under the influence of steadily applied load varied from 0.5 to 2.0 kN. The data collected during experimentation have been used to evaluate thermal performance parameters such as maximum pressure, flow rate and effective temperature of the bearings under study. Findings It has been observed experimentally that two lobes of pressure and temperature have been obtained for both the elliptical and orthogonally displaced journal bearing. The negative pressure zone (cavitation area) has been observed to be reduced along the circumference for both the journal bearings which results in less thermal degradation of an oil as compared to circular journal bearing. The oil film pressure and temperature increases with the increase in radial load of both the bearings. The maximum temperature rise of oil film is more in case of elliptical bearing as compared to the orthogonally displaced bearing. Originality/value The experimental data presented in this paper will help the designers to select such kind of non-circular journal bearing for various applications. The designed bearings have resulted in reduced cavitation zone and two positive pressure lobes have been observed which may result in application of such bearings as an alternate for circular journal bearing.

Oil Film Damping Analysis in Non-Newtonian Transient Thermal Elastohydrodynamic Lubrication for Gear Transmission

2018 ◽  
Vol 85 (3) ◽  
Author(s):  
Zeliang Xiao ◽  
Zuodong Li ◽  
Xi Shi ◽  
Changjiang Zhou
Keyword(s):  
Thermal Effect ◽  
Rotation Speed ◽  
Impact Resistance ◽  
Elastohydrodynamic Lubrication ◽  
Tangential Direction ◽  
Maximum Temperature ◽  
Spur Gears ◽  
Oil Film ◽  
Tooth Number ◽  
Transient Thermal

The models of normal and tangential oil film damping are established by modeling the viscous-elastic fluid as massless damping elements. The central pressure and film thickness distributions, friction coefficient, and maximum temperature rise with or without considering thermal effect indicate the proposed damping models and the solutions to the damping are valid. Thereafter, the thermal effect on oil film damping is discussed and the effects of contact force, rotation speed, and tooth number of spur gears in line contact non-Newtonian transient thermal elastohydrodynamic lubrication (EHL) on the oil film damping are investigated. The results imply that the larger damping in the normal direction is beneficial to meshing impact resistance and vibration reduction, whereas the smaller damping in the tangential direction is very helpful for fluidity enhancement and friction heat inhibition.

Computation of Thermal Deformation of Thrust Bearing Pad Concerning the Convection by Non-Uniform Oil Flow

2005 ◽  
Author(s):  
Makoto Hemmi ◽  
Koushu Hagiya ◽  
Katsuhisa Ichisawa ◽  
Sukeyuki Fujita
Keyword(s):  
Temperature Distribution ◽  
Thermal Deformation ◽  
Thrust Bearing ◽  
Oil Film ◽  
Thrust Bearings ◽  
Turbine Generators ◽  
Precise Estimation ◽  
Tilting Pad ◽  
Oil Flow ◽  
Water Turbine

Tilting-pad thrust bearings are used to support the loads of large rotating machinery, such as water turbine generators. When such machines are in operation, thermal deformation is so extensive that it is comparable to deformation caused by the pressure of the oil film, and it influences the bearing’s performance. So, the temperature distribution in the pad, which determines the thermal deformation, should be calculated correctly. This requires precise estimation of the convection by the ambient oil at the pad’s surfaces, but the complexity of the pad’s shape and ambient oil flow of oil around it makes this estimation difficult. Using CFD (Computational Fluid Dynamics) software, we computed the temperature distribution in the pad by solving the heat transfer in the pad, in the oil and interfaces of them simultaneously. The thermal and stress deformation were then calculated by the FEM code and is used in oil film analysis to determine the characteristics of the bearing. Comparing its results with the experimental ones validated the computational process.

Oil Film Thickness and Shape for a Ball Sliding in a Grooved Raceway

1972 ◽  
Vol 94 (3) ◽  
pp. 199-208 ◽  
Author(s):  
N. Thorp ◽  
R. Gohar
Keyword(s):  
General Theory ◽  
Film Thickness ◽  
Contact Area ◽  
Elastohydrodynamic Lubrication ◽  
Surface Velocity ◽  
Oil Film ◽  
Pressure Dependent Viscosity ◽  
Ball Surface ◽  
Lubricated Contact ◽  
Dependent Viscosity

The behavior in the lubricated contact area of a driven ball sliding in a conforming glass groove, is studied. Interferometry is used to measure the oil film. Coupled ball surface velocity components are provided by angling the drive, while loads and speeds are varied in order to cover a range of conditions from undistorted surfaces to elastohydrodynamic lubrication. A general theory for lubrication with, no distortion and pressure-dependent viscosity, is developed and compared with experiment. Ball spin is found to have only a small effect on the oil film thickness.

scholarly journals The Piston Ring-Cylinder Bore Interface Leakage of Bent-Axis Piston Pumps Based on Elastohydrodynamic Lubrication and Rotation Speed

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Lvjun Qing ◽  
Lichen Gu ◽  
Yan Wang ◽  
Wei Xue ◽  
Zhufeng Lei
Keyword(s):  
Film Thickness ◽  
Piston Ring ◽  
Rotation Speed ◽  
Elastohydrodynamic Lubrication ◽  
Oil Film ◽  
Proposed Model ◽  
Minimum Film Thickness ◽  
Oil Flow ◽  
Discharge Pressure ◽  
Cylinder Bore

The bent-axis piston pump is the core component of electrohydrostatic actuators (EHA) in aerospace applications, and its wear of key friction interfaces is greatly related to the healthy operation of pumps. The leakage of the piston ring-cylinder bore interface (PRCB), as the important part of the return oil flow of the pump house that commonly assesses the wear of key friction interfaces in piston pumps, is changed with the rotation speed. Thus, the wear of key friction interfaces is usually inaccurate by using the leakage of PRCB. In order to obtain the relationship between the PRCB leakage and the rotation speed, an elastohydrodynamic lubrication model is proposed. First, the proposed model includes a minimum film thickness model of PRCB to analyze the dynamic change of oil film of PRCB when subject to the elastohydrodynamic lubrication. After that, a mathematical model of PRCB is induced by combining the minimum film thickness model with the flow equation, which helps produce the effects of the oil film on the leakage of PRCB. The proposed model is verified by numerical simulation and experiment. The results show that the leakage of PRCB has a negative effect on the return oil flow of the pump case in the range of rotation speed of 700–1300 r/min and discharge pressure of 10–20 MPa. Furthermore, the leakage of PRCB is proportional to the rotation speed, but the return oil flow of the pump case is decreased. The effects of rotation speed are enhanced under the high discharge pressure conditions.

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