The Lubricant Flow Structure and Pressure Generation in a Journal Bearing With Diamond-Knurled Stator Surface

Journal bearings are popularly used in turbo machinery. The load carrying capacity and the dynamic behavior, stiffness and damping, of a journal bearing are determined by lubricant and bearing parameters: clearance, and shaft diameter and rotation speed, and surface morphology of the rotor and stator surfaces. It has been found that journal bearings with roughened stator surfaces have better performance. This paper presents a numerical investigation on the flow of lubricant in the knurls, in the fluid film between the rotor and the land of the stator, and the pressure generated on the rotor surface in a knurled journal bearing. Three computational models are developed and compared. The full Navier-Stokes equations are solved with a finite volume algorithm to simulate the fluid flow and the pressure generation. The total forces on the rotor surfaces are correlated to the bearing eccentricity and compared to the forces on the smooth bearing shaft of the same clearance. The effects of knurls on the bearing performance will be analyzed and guidance on further investigations on knurled journal bearing is presented.Copyright © 2007 by ASME