Effect of Surface Texture Depth with Various Geometric Shapes on the Steady-State Performance and Dynamic Stability of Noncircular Lobed Journal Bearings

The widespread use of journal bearings in rotating machinery has intensified the need to optimize their operational performance. A key determinant of bearing efficiency lies in the lubricant film thickness between the rotor and bearing surface. Recent studies demonstrate that strategically engineered surface textures can effectively modulate film thickness and enhance both static and dynamic characteristics of bearing. This investigation specifically examines how cubic, cylindrical, and semi-ellipsoidal texture geometries at varying depths influence the performance of noncircular two-lobe bearings. Through finite element analysis, the study evaluates critical performance parameters including load capacity, rotor attitude angle, critical mass threshold, and whirl frequency ratio to establish texture–depth relationships with system stability and operational efficiency. The analysis reveals that texturing the maximum pressure zone in lobe 2 significantly enhances bearing performance, with semi-ellipsoidal, cylindrical and cubic geometries, respectively. Also, the results demonstrate that texture geometry and depth significantly influence two-lobe bearing performance. Optimal enhancements in load capacity, whirl frequency reduction, and critical rotor mass occur at texture depths below the bearings clearance space width, with performance peaking before gradually declining as depth increases further. Notably, texture application in low-pressure or cavitation regions generally yields diminished or even counterproductive effects. The findings demonstrate that cubic textures provide optimal bearing performance across all depth ranges, with cylindrical and semi-ellipsoidal geometries ranking second and third, respectively, in comparative analysis.