Performance evaluation of nanoparticles based lubricants on static thermal behaviour of non circular journal bearings

Abstract

In the present study, performance of nanoparticles based lubricants has been studied on static thermal behaviour of non-circular journal bearings. Two types of nanoparticles, namely, CuO and TiO2 with 0.5wt%, 1wt% and 2wt% concentrations have been separately added in three commercially available oils of different viscosity grades. The effect of nanoparticles on thermo physical properties of oil has been taken into account to model the bearing performance parameters such as pressure distribution, load capacity, oil temperature and power losses at different eccentricity ratios and journal speeds. Finite difference method has been applied for solving Reynolds equation by generating a model using MATLAB® R2020a software. Bearing model was generated by taking into account the modified Krieger Dougherty method to determine viscosity at different combinations of oils and nanoparticles. Firstly, viscosity was kept constant to compute the isothermal pressures, and then hydrodynamic pressures have been alculated by incorporating viscosity temperature relationship. Energy equation was also solved with finite difference method by applying Parabolic Temperature Profile Approximation technique. The temperature distribution was computed till a converged solution for hydrodynamic pressure and temperature loop was achieved. The pressure and temperature values at all the nodal points were calculated by solving Reynolds and Energy equations, respectively. Numerical modeling results were validated by experimentally studying the hydrodynamic pressure and oil film temperature distribution in noncircular journal bearings. The results revealed that the elliptical journal bearing with titanium dioxide gave optimum static thermal performance characteristics for AW 32 lubricating oil. Thus, use of nanoparticles based lubricants has enormous potential for significantly increasing the hydrodynamic pressure and load capacity of journal bearings with slight increase in oil temperature leading to static thermal performance optimization of it.