Innovative insights into nanofluid-enhanced gear lubrication: Computational and experimental analysis of churn mechanisms

Abstract

This study offers unique insights into the churn lubrication mechanism in gear transmission systems through the utilization of nanofluids for the first time. Various performance parameters of the prepared nanofluid lubrication oil are measured, along with the discussion of suspension stability. Based on the overset mesh method and VOF multiphase flow model, a rotating fluid domain calculation model considering the nanofluid-air two-phase is proposed. The high-speed nanofluid lubrication experiment platform is established to track churn phenomena and identify the oil volume fraction on the gear surface. Comparing simulation results with experimental data confirms the calculation accuracy in depicting oil flow and churn lubrication. Result shows that the interaction between droplets and the gear surface involves splash, rebound, adhesion, and diffusion. The nanofluid exhibits improved adsorption, resulting in a higher oil volume fraction. When the rotation speed is increased, intensified oil spatter and atomization are observed. The ranking of nanofluid lubrication performance is Al2O3, SiO2, Fe3O4, CuO, and TiO2 particles, which are approximately aligned with contact angle magnitudes. For 3 % nanoparticles concentration, less oil is swung off, more is drawn into the gear meshing zone, and subsequently squeezed out. Image recognition results align with numerical simulation, indicating that the oil distribution of nanofluid is better than that of base fluid lubrication. This work serves as a foundational exploration for future nanofluid lubrication and heat dissipation, offering insights into preventing oil film rupture, tooth surface wear, gluing and other failure mechanisms.