In this paper, an investigation of hydrodynamic performance for journal bearing lubricated by thin film is performed by three-dimensional CFD (computational fluid dynamic). Two regimes, i.e. laminar and turbulent regimes are of main interest. The sliding velocity was varied from 3000, 5000 and 10000. The numerical simulation shows that the velocity magnitude of the journal has a strong effect on the hydrodynamic pressure. In addition, it is found that an appropriate modelling of flow regime affects the predicted lubrication performance. From the overall analysis, both using laminar and turbulent regimes, the distribution of static hydrodynamic pressure shows a similar trend. It is also found that at the beginning of the contact, the static pressure is low, and then, it gradually increases to the highest point, and finally drops significantly.
Keywords: Computational fluid dynamic (CFD), journal bearing, lubrication, turbulent
INTRODUCTIONRecently, a thin film lubricated journal bearing has attracted much attention. Following the progress in numerical analysis and technology, many researchers began to use commercial computational fluid dynamics (CFD) program in their investigations. The main advantage of CFD code is that it uses the full NavierStokes equations and provides a solution to the flow problem based on finite volume method (Panday et al., 2012). Therefore, the CFD methods are applicable in very complex geometries.Gertzos et al., (2008) worked on CFD method of lubricated journal bearing by Bingham lubricant. They solved Navier-Stokes equations by using the FLUENT package and compared the results of the developed 3-D CFD model with theoretical and experimental results of previous investigations, for both Newtonian and Bingham lubricants, and found to be in a very good agreement.Stefani and Rebora (2009) worked on using Quasi-3D mass-energy-conserving method by extending a previous mass and energy-conserving algorithm. The proposed method produced temperature profiles in a good agreement with the experimental results, whenever consistent boundary conditions were induced. Taking into account the thermal deformations of the kinematic pair, it leads us to improve the reliability of the model. Gururajan and Prakash (2002) investigated the effect of surface roughness in a narrow porous journal bearing. It was shown that for a smooth case, the results based on an approximate analysis could be safely used for thin-walled bearings of low permeability. Peng et al., (2007) developed a new form of the Reynolds equation. The new Reynolds equation for the lubricating film was solved by using Finite Volume (FV) discretization. According to the numerical solution, the journal squeeze effect and the pad rotation effect on film force were discussed.