Hydrodynamics of plain bearings with smooth liners


Аuthors

Nazarenko Y. B.1*, Marishkin V. V.2

1. Lyulka Experimental Design Bureau, branch of the United Engine Corporation – Ufa Engine Industrial Association, 13, Kasatkina str., Moscow, 129301, Russia
2. Lytkarinsky Machine-building Plant-branch of the United Engine Corporation Ufa Engine Industrial Association, Lytkarino, Moscow region, Russia

*e-mail: nazarenko.yuri@gmail.com

Abstract

Liquid friction in plain bearings is considered on the basis of the hydrodynamic theory of lubrication.
This theory is based on solutions of differential equations of hydrodynamics of a viscous fluid, which relate pressure, velocity and resistance to viscous shear.
When a fluid moves between two plates, one of which is loaded with a force, at a certain inclination of the plate and flow rate, pressure arises in the flow, which compensates for this force.
The theory of fluid flow between plates has been applied to lubricant flow in plain bearings.
In liquid friction, the working supporting surfaces of the shaft (trunnion) and liner (bearing socket) are separated by a layer of oil, the thickness of which must be greater than the sum of the heights of the roughness of the two surfaces. In this case, the reaction of the rotor on the support is compensated by the hydrodynamic forces of the oil flow of the convergent film.
 In radial plain bearings, the convergent lubricant film is inherent in the bearing design itself. It is formed by displacing the center of the shaft downward in the direction of the vertical force and in the direction of rotation. The minimum clearance is formed along the line of the centers of displacement of the center of the shaft and the center of the bearing.
The thickness of the oil layer in the working area of the bearing for half of its circumference was set by a trigonometric function, which allows the clearance to be approximated with sufficient accuracy with a ratio of the maximum clearance value to the minimum from 1 to 5.
The distribution of hydrodynamic pressure along the length of the clearance and the maximum radial hydrodynamic forces supporting the rotor shaft on an oil lining were obtained.
A calculation was carried out on a plain bearing model for certain bearing parameters and the distribution of hydrodynamic pressure presented in the diagram was obtained, and the lifting hydrodynamic force supporting the rotor on the oil layer was determined.
Based on the analytical determination of hydrodynamic forces in the convergent film of a plain bearing due to the pressure of the oil flow passing through the narrowing annular clearance, a technique has been developed that allows to setup plain bearing parameters and oil consumption.

Keywords:

rotor, shaft, plain bearing, hydrodynamic forces, convergent film

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