CFD Analysis of the Lubricant Flow in the Supply Groove of a Hydrodynamic Thrust Bearing Pad

Inlet temperature is one of the main inputs in all models for analysis of fluid film bearings performance. On the other hand inlet temperature distribution and also oil speed distribution at the inlet is the result of flow phenomena in the gap between bearing pads. These phenomena are complex and in many cases additionally affected by a special bearing design incorporating various arrangements of forced oil supply to the gap between pads. The reason for such arrangements is more efficient introducing of the lubricant cooled in an external cooling system to the oil film. Not much is known about flow phenomena in the gap between the pads and even less if the bearing is fitted with any kind of directed lubrication system. One of those special bearing arrangement is a leading edge groove (LEG) design described by Mikula [1] Experimental results showed that LEG lubricating system in comparison to flooded lubrication caused about 10–20°C drop in maximum temperature in high-speed bearings. But not much is known of potential benefits of using this lubrication method in large low-speed bearings applied in water turbines. There were no attempts of adaptation of this lubrication system to large size bearings. In this case modeling is necessary because of large cost of experiments. Contemporary computer codes of Computational Fluid Dynamics (CFD) enable one to study flow between bearing pads or in lubricating groove and even to build models of a whole hydrodynamic bearing within CFD systems. Some results of modeling lubricant flow in the gap in a bearing with a directed lubrication system are presented in the paper.