Mahdi Zare Mehrjardi - PhD Student, Department of Mechanical Engineering, Yazd University
Reza Rashidi Meybodi - Assistant professor, Department of Executive Engineering, Payame Noor University, Tehran, Iran

In this work performance characteristics of two, three and four lobe noncircular journal bearings of micropolar fluids are presented. Lubricating oil containing additives and contaminants is modeled as micropolar fluid. The modified Reynolds equation is obtained using the micropolar lubrication theory and solving it by using generalized differential Quadrature (GDQ) method as a simple, efficient and high order numerical technique. The performance characteristics in terms of load carrying capacity, coefficient of friction, attitude angle and side leakage flow are determined for various values of size of material characteristic length, coupling number, aspect and eccentricity ratio and the mount and tilt angles. The results show compared with Newtonian fluids, that micropolar fluid exhibits better efficiency. Also results show that micropolar fluids exhibit increase in load carrying capacity but decrease in coefficient of friction, attitude angle and side leakage flow. 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. Also results show that the variation of Assemblage Parameters (tilt and mount angles) can has variable effects on noncircular lobed journal bearing performance parameters. Among the three types of noncircular bearings considered, the effect of Design and Assemblage Parameters is more significant for two lobe bearings in comparison to other type of noncircular three and four lobe bearings.

noncircular journal bearing, micropolar lubricant, Design parameters, Assemblage Parameters, GDQ method