Numerical analysis of hydrodynamic journal bearings lubricated with ferrofluid

Abstract

The current work focuses on studying the hydrodynamic characteristics of flow in journal bearings lubricated with ferrofluid. The bearing has an infinite length and operates under incompressible laminar flow and steady conditions. Assuming linear behaviour for the magnetic material of the ferrofluid, the magnetic force was calculated. The displaced current-carrying infinitely long wire is used as a field model. This model gives a field distribution with a gradient in the circumferential and radial directions. The analysis is based on the numerical solution of the full Navier—Stokes equations using computational fluid dynamics techniques. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid and the governing equations are transformed in the computational domain. Discretized forms of the transformed equations are obtained by control volume method and solved by the SIMPLE algorithm. In the current study, cavitation effects are also considered by an appropriate cavitation model. To validate the computational results, a modified Reynolds equation has been obtained and solved by finite‐difference method. The results indicated that comparing with a conventional lubricant, the ferrofluid as a lubricant improves the hydrodynamic characteristics of journal bearings and provides a higher load capacity and a reduced friction coefficient. It will be evident that the other bearing characteristics depend on the applied field model. Numerical results of this analysis can be used to investigate the oil flow pattern and the hydrodynamic characteristics of journal bearings lubricated with ferrofluid.