Numerical Analysis of Three-Lobe Hydrodynamic Journal Bearing using ANSYS

Abstract

Journal bearings are used on a variety of different rotating and reciprocating machines to support shafts that are rotating inside a bearing. In contrast to anti-friction type bearings where the primary mechanism is rolling action of contacting components, journal bearings operate by supporting the load of the shaft on a pressurized oil film. Journal bearing has a layer of lubricant (oil) separating two parts through fluid dynamic effects. Reynolds equation is used to obtain the pressure equation which can be integrated to obtain stiffness and damping coefficients. This pressure generates reaction forces on shaft and tries to keep it stable. The oil film in journal bearing provides stiffness and damping. The film of lubrication is analytically modeled in ANSYS workbench and by perturbation method the damping coefficients are obtained. Simple method to predict vibration characteristics of multi lobe journal bearing using FFT analyzer for vibration analysis is done in this study.