Effect of the geometric shape and position of surface textures on the dynamic stability of noncircular journal bearings

Abstract

Improving the performance of oil journal bearings is crucial due to their widespread use as supports for rotating components in industrial machinery. One of the latest methods proposed by researchers to enhance journal bearing efficiency involves creating regular surface textures on the bearing elements. This study examines the performance of noncircular two lobe hydrodynamic bearings featuring cubic, cylindrical, and semi-ellipsoidal surface textures at various positions. To assess the effects of surface textures on journal bearing performance, the governing Reynolds equation is modified to incorporate changes in lubricant film thickness caused by the textures. Additionally, the dynamic equations of rotor motion, based on a linear dynamic approach, are solved alongside the modified Reynolds equation using the finite element numerical method under Reynolds boundary conditions to identify cavitation zones across the lobes. Subsequently, the incompressible lubricant pressure profile and the equivalent stiffness and damping coefficients of the support system are determined. Finally, the static and dynamic performance of two lobe bearings with various applied textures is calculated. The results indicate that creating textures in the high-pressure region of the lower lobe leads to an increase in oil pressure, thereby enhancing the performance of two lobe bearings. Conversely, when textures are created in low-pressure areas, a decrease in oil pressure occurs, resulting in reduced static performance parameters and dynamic stability compared to non-textured bearings. Furthermore, the findings suggest that the impact of texture on the two lobe bearings performance is amplified as their geometry changes from semi-ellipsoidal to cylindrical and cubic types, respectively.