A simplified thermohydrodynamic lubrication model for application to the design of cylindrical journal bearings with two-axial oil grooves

Abstract

Thermohydrodynamic lubrication (THL) models have been applied to predict the performances of journal bearings that support industrial rotating machineries. The final goal of this study is to propose a THL bearing design method of cylindrical journal bearings with two-axial oil grooves by using the model expressions, which are derived from a database constructed by the THL predictions and can predict the reasonably accurate bearing performances over a wide range of operating conditions and bearing specifications. In the present article, after the previous simplified model, which predicts the bearing performances from only four dimensionless numbers — Sommerfeld number, bearing width-to-diameter ratio, Peclet number and Khonsari number, is shown to poorly predict the performances, a simplified THL model is newly proposed for the database of the bearing performances. This model is derived by modifying the precedent high-accuracy THL model and predicts the bearing performances from the same four dimensionless numbers as the previous simplified model. Compared with some measurements in test rigs of the bearings, the model proposed is found to predict more reasonably accurate performances of the bearing under fully lubricated conditions than the previous simplified model. It is concluded that the new model is appropriate to the database for the simple easy and straightforward bearing design.

Keywords

• tribology
• themohydrodynamic lubrication model
• cylindrical journal bearing
• two-axial oil grooves
• energy equation for oil film temperature distribution
• bearing performance
• maximum bearing temperature