Lubrication Performance of Two-lobe Bearings Considering Effects of Micro-polar Fluids Using the Tsann Roughness Model

In the lubrication theories, the bearing surfaces are generally considered as smooth and without any roughness, but actually these are not accurate. In order to find the bearing performance parameters it is required to solve the lubrication equation. Without necessary simplifications, solving such equation is terribly difficult. By adding the roughness effects to the problem, the necessity of using numerical methods become more obvious. The surface irregularities play an important role in the bearing mechanical behaviors. Such roughness, cause conversion in lubricated film thickness that effect on lubrication parameters. The considered fluids in this investigation were incompressible micro polar fluids that contain ingredients, which will endure the physical stresses and moments. In this article, using the finite element method, the effects of surface roughness on the lubrication of two-lobe bearings performance were proposed. Roughness numerical modeling was approached by the Tsann method. At first, the computer program had been written for the smooth case and then the program was developed for the bearings with roughness on their surfaces. The problem was resolved for two different surface profiles and the results were compared. The results indicate that considering the thickness of lubricant layer with the Tsann roughness theory will increase the pressure distribution and load carrying capacity but it reduce the coefficient of friction and side leakage flow.