Department of Mechanical Engineering, College of Engineering and Petroleum, Kuwait University, P. O. Box 5969, Safat 13060, Kuwait.
E-mail: abdallah@kuc01.kuniv.edu.kw
ABSTRACT
In the present study, the effects of non-Newtonian behavior of the lubricant on the static performance of hydrodynamically lubricated journal bearings were investigated. Three different rheological models, used to simulate the non-Newtonian behavior resulting from blending the lubricant with additives, the power law fluid model, the couple stress fluid model, and the micro polar fluid model. The modified Reynolds equation is presented for each rheological model. The effects of misalignment were also considered. Cavitation effects were considered using Elrod’s cavitation algorithm. Elastic deformation of the bearing surface was estimated in a direction normal to the bearing surface using the thin liner model. The film pressure was solved numerically with cavitation boundary conditions and then various bearing characteristics were calculated. The effects of non-Newtonian behavior on bearing performance characteristics such as pressure distribution, load-carrying capacity, friction coefficient, and misalignment moment for the three non-Newtonian fluid models were analyzed. The results showed that lubricant additives significantly increased the load carrying capacity and reduced the coefficient of friction as compared to the Newtonian lubricants.
Keywords: hydrodynamic lubrication ; journal bearings ; non-Newtonian fluids.