Computational Investigation of Oil Film Pressure Profile in Journal Bearings

Abstract

Lubrication of journal bearing in ship shafting systems is facing a problem in the slow speed range, where oil film created pressure depends on shaft speed, among many other factors. Hence, the slower the speed the lower the pressure will be, which shifts lubrication from hydrodynamic to boundary one. An experimental journal bearing test rig (JBTR) has been designed and established to simulate typical journal bearing for ship’s shafting system. A theoretical validation study has been undertaken and good agreement with the test rig pressure readings was found. The test rig is capable of carrying out wide range of tests to investigate oil film pressure profile dependence on many parameters regarding design modification, oil properties, material properties, and many other factors. A new Computational Fluid Dynamic (CFD) model has been built for the sake of coupling future experimental investigations with computerized ones. The CFD model was created using the well-known CFD package Ansys ver. 15.0. The effect of shaft speed on oil film pressure profile was studied using the CFD model as a verification test. The model results were contrasted to the experimental results and an acceptable deviation range was found.