Mahdi Zare Mehrjardi - PhD Student, Department of Mechanical Engineering, Yazd University
Asghar Dashti Rahmatabadi - Associate professor, Department of Mechanical Engineering

In this work generalized differential Quadrature (GDQ) method as a simple, efficient and high order numerical technique is used for the solution of modified Reynolds equation to obtain the performance of hydrodynamic circular and noncircular four-lobe journal bearings lubricated with micropolar fluid. Effects of micropolarity characteristics of lubricant, design and assemble parameters, namely the nondimensional characteristic length, coupling number, aspect and eccentricity ratio, mount and tilt angles on the performance parameters of these bearings have been investigated. The computed results show that depending on the characteristic length and the coupling number, there will be significant changes on the performance parameters. These results show, compared with Newtonian fluids, that micropolar fluids exhibit increase in load carrying capacity but decrease in coefficient of friction, attitude angle and side leakage flow. Also it is observed that the effect of micropolar fluids is morepronounced at high coupling numbers. It is observed that the effect of micropolar fluids is more pronounced at high coupling numbers. Results show that though noncircularity of journal bearings can have certain advantages in bearing operation, however, the magnitude of pressure distribution developed in bearings decreases with increasing in noncircularity or decreasing of preload factor in bearing. Decrease in magnitude of pressure causes a decrease in load carrying capacity, attitude angle but increase in coefficient of friction in bearings. Also results show thatthe variation of mount and tilt angles can has variable effects on noncircular four-lobe journal bearing performance parameters.

noncircular journal bearing, four-lobe, micropolar lubricant, tilt and mount angle, GDQ method