Effect of Using Nano Lubricant Containing TiO2 Particles on the Performance of Noncircular Two Lobe Journal Bearings

Development of nanotechnology and related sciences in the field of lubrication has led to applying nano particles in combination of the common lubricants as one of the most new solutions proposed by the tribology researchers to improve the performance of this type of support systems. In this study, the effect of TiO2 nano particles concentration combined with the base SAE30 oil on the steady state and dynamic stability performance of hydrodynamic two lobe journal bearings is investigated. For this purpose, after modifying the governing Reynolds equation of hydrodynamic lubrication using nano fluid theory and assuming the harmonic limit cycle oscillation of the rotor center around the static equilibrium point based on the linear dynamic model, the stability performance of two lobe bearings are analyzed. Finally, the static and dynamic stability characteristics for different concentration of the nano particle according to the bearing non circularity are obtained using the finite element method (FEM). The results show that the static and stability performance parameters of the non circular two lobe bearings, including the load carrying capacity, coefficient of friction, critical mass of the rotor and the whirl frequency ratio improve by increasing the concentration of TiO2 nano particles added to the base oil, especially for solid volume fraction less than %0.02 and the magnitude of performance variations is also amplified by reducing the amount of bearings non circularity.