CFD-based lubrication performance analysis and structural assessment of a multi-pad adjustable fluid film bearing

Adjustable or controllable bearings provide a promising approach to overcome design limitations and adapt to real-time operating conditions in rotating machinery. This study numerically investigates a novel four-pad clearance-adjustable bearing geometry for active rotor–bearing systems, focusing on structural rigidity during pad adjustment and improved lubrication performance and durability. A two-stage numerical approach is used: (i) Computational Fluid Dynamics (CFD) analysis to evaluate hydrodynamic pressure and load capacity under varying pad configurations, L/D ratios, speeds, and slip intensities and (ii) Finite Element Method (FEM) analysis to examine the structural response of pad geometry under different loading conditions. From CFD analysis, results show that negative radial–negative tilt configurations produce higher pressures and load capacity, especially at lower L/D ratios and higher speeds. CFD results further indicate that slip intensity measurably alters the hydrodynamic pressure distribution and load-carrying capacity, highlighting the need to account for slip effects in adjustable bearing performance evaluation. Structural evaluation shows that steel pads provide the highest stiffness, while aluminium and brass support lighter designs within safe stress limits. Fatigue and modal analyses further confirm structural safety and resonance avoidance. The CFD and FEM results reveal geometry-dependent performance balances and provide practical guidance for pad adjustment, material selection, and the experimental development of adaptive adjustable bearing systems aimed at reduced maintenance and improved long-term efficiency.