Inlet mixing in a highly loaded tilting-pad thrust bearing

The mixing processes in the inlet region of high-speed journal and thrust bearings provide essential boundary conditions for the thermo-elasto-hydrodynamic (TEHD) analysis of their operating behavior. This paper investigates the inlet mixing between hot oil from the upstream pad and fresh oil supplied in the space between pads region for a highly loaded, flooded lubricated tilting-pad thrust bearing. A combination of Computational Fluid Dynamics (CFD) and TEHD analyses based on an extended version of a model for oil flow and fluid temperature inlet mixing earlier introduced by the authors for journal bearings provides a novel insight on the dominant inlet mixing processes in hydrodynamic thrust bearings. Predicted bearing metal and runner temperatures representing a consequence of the inlet mixing process are validated with test data that varies runner speed, pivot offset and the angular span of the inlet. Selected characteristic distributions such as the inlet temperatures of the downstream pad are compared and their origin is analyzed based on the modeled physical effects. Results indicate that the essential phenomena are covered by the TEHD inlet mixing model and justify its basic application to thrust bearings as good to excellent agreement between measurement and prediction is achieved. Possible model extensions to describe high-speed applications are discussed.