Hydrodynamics of plain bearings with oil leaks


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 with smooth liners is considered when oil leaks through the side ends of the bearing.
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 wedge.
Based on the analytical solution of the Navier-Stokes hydrodynamic equations, the patterns of fluid flow in sliding bearings and hydrodynamic pressure were established without oil leaks.
This theory is based on solutions of differential equations of hydrodynamics of a viscous fluid, which relate pressure, velocity and resistance to viscous shear.
To eliminate overheating of the bearing, it is cooled. This is realized when a new portion of oil arrives with a controlled outflow through the side ends of the bearing  
An analysis of the influence of oil leaks was carried out when liquid flows between flat plates using a numerical method in the ANSYS CFX software package.
In this case, the liquid flow expense at the outlet of a flat plate with and without oil leaks with closed ends is approximately the same, but at the inlet of plates with oil leaks it increases by the amount of leaks compared to closed ends.
Then the distribution of hydrodynamic pressure in a plain bearing with oil leaks will be obtained from the solution of oil flow without leaks, but with an increase in oil flow rate at the inlet.
The values of hydrodynamic pressure along the length of the gap and the maximum radial hydrodynamic forces supporting the rotor on the oil lining were obtained, and a model of the sliding bearing was calculated to determine its parameters.
Based on the analytical determination of hydrodynamic forces in the wedge clearance 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.

Keywords:

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

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