Wear simulation for the journal bearings operating under aligned shaft and steady load during start-up and coast-down conditions

2016 ◽  
Vol 97 ◽  
pp. 440-466 ◽  
Author(s):  
Sang Myung Chun ◽  
Michael M. Khonsari
Keyword(s):  
Journal Bearings ◽  
Wear Simulation ◽  
Start Up ◽  
Steady Load

Model-Based Investigation of Friction During Start-Up of Hydrodynamic Journal Bearings

1995 ◽  
Vol 117 (4) ◽  
pp. 667-673 ◽  
Author(s):  
A. Harnoy
Keyword(s):  
Friction Model ◽  
Journal Bearings ◽  
Time Variable ◽  
Stribeck Curve ◽  
Dynamic Friction ◽  
Stick Slip ◽  
Friction Characteristics ◽  
Start Up ◽  
Variable Friction ◽  
Steady Velocity

An analysis is developed for the time-variable friction during the start-up of a rotor system. The analysis is based on a dynamic friction model that has been developed from the theory of unsteady lubrication and can describe the observed friction characteristics. The model reduces to the Stribeck curve of friction versus steady velocity, and shows hysteresis curves in oscillating velocity. The “Dahl effect” of a presliding displacement before the breakaway is also included. The results indicate that the friction characteristics and energy friction losses, during the start-up, depend on a set of dimensionless parameters that represent the bearing as well as the dynamic system. The study shows that appropriate design and operation can prevent stick-slip friction and minimize wear during start-up.

Transient tribo-dynamic model for journal bearings during start-up considering 3D thermal characteristic

2020 ◽  
Vol 144 ◽  
pp. 106123 ◽  
Author(s):  
Guo Xiang ◽  
Yanfeng Han ◽  
Tao He ◽  
Jiaxu Wang ◽  
Ke Xiao ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Thermal Characteristic ◽  
Journal Bearings ◽  
Start Up

An Experimental Investigation on Friction Coefficient in Plain Journal Bearings During Start-Up

2008 ◽  
Author(s):  
J. Bouyer ◽  
M. Fillon
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Experimental Measurements ◽  
Air Bearings ◽  
Specific Pressure ◽  
Thrust Bearings ◽  
Start Up ◽  
Transient Thermal

The start-up friction coefficient is a parameter which is very useful for engineers who design hydrodynamic bearings. It is most often issued from an approximation. Several studies can be found in the literature on this topic but most of them are concerned with air bearings or are only numerical. Some studies are more general and deal with the transient thermal behaviour in journal bearings as well as in thrust bearings. Other studies deal with the friction coefficient during running, at a fixed rotational speed. The aim of this study is to provide experimental measurements of the bush torque during start-up of plain journal bearings, varying the specific pressure. Thus, the friction coefficient at start-up (deduced from measurements) is obtained for four different bearings varying feeding conditions, radial clearance and length.

Numerical analysis on the start behavior of rough journal bearings during the gear pump meshing cycle

2020 ◽  
Vol 234 (8) ◽  
pp. 1275-1295
Author(s):  
Jiaxing Zhu ◽  
Huacong Li ◽  
Jiangfeng Fu ◽  
Xianwei Liu ◽  
Shang Wang
Keyword(s):  
Hydrodynamic Lubrication ◽  
Internal Flow ◽  
Simulation Method ◽  
Journal Bearings ◽  
Gear Pump ◽  
Film Rupture ◽  
Load Fluctuation ◽  
Start Up ◽  
Lubrication Performance ◽  
Lubrication Characteristics

In this paper, the transient lubrication characteristics of hydrodynamic journal bearings during the external gear pump meshing cycle are studied. In the bearings lubrication calculation part, a numerical model is developed to assess the transient lubrication during the initial start-up of an aero gear pump. The model takes into account the effects of surface topography, asperities contact, and pump start-up speed. In the pump simulation part, the flow inside pump and bearing load environment are analyzed by a computational fluid dynamics model. Then a simulation method is presented to solve the problem of pump-bearings system, considering the pump’s influence during bearings lubrication calculation. To gain insight, results of a series of simulations with illustrative examples are presented. The variation of the startup lubrication performance under load conditions corresponding to the pump internal flow field is acquired. The results show that bearings operate from mixed-lubrication to hydrodynamic-lubrication state with changed load-supporting effects during the startup. The load-supporting effects and film rupture boundary are directly related to the pump load fluctuation, but the center trace is slightly influenced except on the hydrodynamic-lubrication state.

Transient Thermoelastohydrodynamic Study of Tilting-Pad Journal Bearings—Application to Bearing Seizure

1998 ◽  
Vol 120 (2) ◽  
pp. 319-324 ◽  
Author(s):  
P. Monmousseau ◽  
M. Fillon ◽  
J. Freˆne
Keyword(s):  
Hydrodynamic Limit ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Safe Operation ◽  
Thermal Limit ◽  
Start Up ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
Tilting Pad Journal Bearings

Nowadays, tilting-pad journal bearings are used under more and more severely demanding operating conditions. Three limits of safe operation were defined (Leopard, 1976): the hydrodynamic limit, the mechanical limit and the thermal limit. The purpose of this study is to determine the hydrodynamic limit of safe operation during start-up for a tilting-pad journal bearing. During start-up, the rapid increase of the temperature in the bearing solids leads to the thermal expansion of both the pads and the shaft. The operating bearing clearance decreases and, when it tends toward zero, seizure occurs. The evolution of the main characteristics (temperature, pressure, film thickness and displacements) versus time is analyzed in the case when a seizure occurs.

Thermally Induced Seizures of Journal Bearings

1989 ◽  
Vol 111 (2) ◽  
pp. 288-292 ◽  
Author(s):  
K. F. Dufrane ◽  
J. W. Kannel
Keyword(s):  
Journal Bearings ◽  
Supply System ◽  
Simple Theory ◽  
Thermally Induced ◽  
Start Up ◽  
Theoretical Predictions ◽  
Bearing Friction

The paper presents a simple theory for predicting seizure times for journal bearings. Under conditions of insufficient lubrication when bearing friction is high, seizure is predicted to occur in less than 20 seconds of operation. Insufficient lubrication can occur during bearing start-up, application of unusual loads, or as a result of an interruption of the lubricant supply system. Three examples where bearing seizure has been observed are discussed and the actual times to seize are compared with theoretical predictions. The actual seizure times are slightly less than predicted by theory, which is probably the result of bearing imperfections or uneven loading not considered in the theory.

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