Lubrication Analysis of Journal Bearing and Rotor System Using CFD and FSI Techniques

Abstract

Along the development of software and hardware, more and more complex engineering problems can be predicted using a computational approach. For a complex bearing-rotor system, several lubrication models have been developed based on the Computational Fluid Dynamics (CFD) technique where a general Navier-Stokes equation is usually considered. In this paper, three different journal bearing models were simulated using a CFD and Fluid Structure Interaction (FSI) technique to investigate the interaction of the lubrication of the journal bearing and the dynamics of the shaft: a pure fluid bearing model, an FSI squeeze-film model and a bearing-rotor FSI model. The first two models were built to compare the CFD and FSI methods with the solution predicted from the classical Reynolds equation and two different boundary conditions were adopted, Sommerfeld and Gümbel. The results of both of these models were compared with the analytical solutions and good agreements were found. The combined CFD and FSI method was subsequently used to study the lubrication performance of the rotor-bearing system. An elastic shaft was used in the full coupled bearing-rotor FSI model, as well as the Gümbel boundary condition. The load applied on the model included a vertical load and a rotation, representative of real working conditions of an experiment of marine journal bearing. Future more complex models will be developed to investigate more realistic rheological properties of the lubricant and the complex interactions between the lubrication of the journal bearing and the dynamics of the shaft using the CFD and FSI method.