Dynamic and stability performance improvement of the nano-lubricated journal bearings with surface waviness

The current study involves numerical investigations to determine the combined impact of surface waviness in the circumferential, axial, and both directions, along with the inclusion of nanoparticles in lubricants, on the dynamic performance and stability of journal bearings operating at lower and higher eccentricity ratios. The copper oxide and cerium oxide lubricant additives at various temperatures and concentrations is added to base lubricant. The modified Reynolds equation controls the flow of incompressible nanolubricant through the clearance of a wave journal bearing system. Based on Stokes micro-continuum theory, the modified Reynolds equation is solved by applying the finite element method to get the bearing performance characteristics parameters. According to the calculated results, the waviness on the bearing surface increases threshold speed, damping, and stiffness coefficients, and the maximum enhancement is found in the case of circumferential waviness with the addition of 0.5% weight fractions of copper oxide and cerium oxide in lubricant at 90°C in comparison with mixed or axial waviness. In addition, as the wave amplitude increased, the stability of the bearing improved.