Experimental and CFD analysis of cavitation in three-lobe journal bearings lubricated with and without TiO₂ nanolubricants

Abstract Hydrodynamic journal bearings (HJBs) are widely used in high-speed rotating machinery owing to their high load capacity and vibration suppression capabilities; however, cavitation in the diverging film region often undermines their performance and reliability. This study presents an integrated experimental numerical investigation of three-lobe HJBs lubricated with titanium dioxide (TiO₂)-based nanofluids and Mobil DTE 24 oil at 500, 750 and 1000 RPM. Circumferential pressure distributions were measured using an experimental test rig for base oil (Mobil DTE 24) and a 0.5 wt.% TiO₂ nanolubricant. Also, CFD simulations were carried out in ANSYS employing a mixture multiphase model coupled with the Zwart Gerber Belamri (ZGB) cavitation model. The results showed that TiO₂ nanoparticles increased peak hydrodynamic pressures, alleviated negative pressures in diverging zones and significantly suppressed cavitation across all operating speeds. Numerical predictions closely matched experimental measurements, with deviations within ± 6%, validating the adopted computational methodology. Pressure profiles further indicated enhanced film stability and improved load-carrying capacity with nanoparticle addition. This study provides benchmark data on the performance of nanolubricants in three-lobe HJBs. It also shows that combining experiments with CFD is an effective approach for evaluating advanced lubrication strategies. The findings provide practical guidance for improving bearing design and increasing reliability in moderate-speed industrial applications.