Effect of Compound Micro Texture Arrangement on Journal Bearing Lubrication Performance

Lubrication performance of composite micro textured surfaces has a certain extent study, however, current research on the arrangement of various textured composite surface bearings must be further advanced. To improve bearing stability, capacity, and reduce the friction factor, the effect of compound micro textures and its arrangement on the static and dynamic characteristics of a hydrodynamic journal bearing system is studied numerically and experimentally, and a comparison between a single and smooth micro texture journal bearing is conducted. The Reynolds equation, oil film thickness equation of the micro texture journal bearing, and the disturbance pressure equation of the oil film in the journal bearing rotor system is numerically solved using the finite difference method and Reynolds boundary condition. Aiming to produce three compound texture shapes (circular composite rectangle, triangular composite rhombic and hexagonal composite crescent), the bearing static characteristics: oil film pressure, bearing capacity, friction drag and end leakage, and the bearing dynamic characteristics: stiffness and damping coefficient are studied under the conditions of four different arrangement modes (Circumferential and axial corresponding parallel, circumferential staggered parallel and axial staggered parallel), and the friction pair tribological properties are further examined using the friction and wear tester. Theoretical and experimental results demonstrate that the compound micro texture bearing obtains greater bearing capacity, smaller friction factor, better dynamic performance and stability than the smooth and single micro texture journal bearings. This is because during the process of fluid lubrication, different composite texture units interact, and the hydrodynamic effect of composite texture units is stronger. The triangular composite rhombic micro texture is more capable of improving the dynamic and static characteristics of the bearing, and reducing the friction coefficient of friction pairs, has a small fluctuation range and the best tribological performance. When the arrangement mode is circumferential corresponding parallel, the texture arrangement of the same shape is parallel to the movement direction, which is conducive to enhancing the wedge and hydrodynamic effect of the bearing. In addition, each micro texture in the pressure rise region ensures that the inflow of lubricating oil is larger than the outflow, which also results in an improved hydrodynamic effect. Thus, when the arrangement mode is circumferential corresponding parallel, it effectively increases the bearing capacity and direct stiffness coefficient, and reduces the bearing friction drag, crossing coupling stiffness coefficient and damping coefficient. Simultaneously, the experiment proves that the friction coefficient and tribological performance of parallel arranged friction pairs corresponding to the circumferential direction are the smallest. In summary, this study demonstrates that investigating the effect of composite texture arrangement on bearing lubrication performance, can improve bearing capacity and stability, reduce the bearing friction coefficient, and provide an important theoretical reference including guidance for the practical application of compound micro textures in industry.