A Study of Seal Lubrication in an Aerospace Fuel Gear Pump Including the Effects of Roughness and Mixed Lubrication

This article describes a hydrodynamic and elastohydrodynamic lubrication analysis of film generation at the rotating contact between the gear tooth end faces and bearing block thrust face seal in a high-pressure aerospace fuel pump. The analysis includes the effect of tilt of the face seal together with elastic deformation and surface roughness of the contacting components. The results of the analysis show that relatively thin hydrodynamic films are generated and that the most likely mode of lubrication is that of mixed lubrication in which part of the load is carried by direct contact at asperity junctions. It is shown that a small improvement in film formation might be obtained by careful profiling or crowning of the end faces of the gears.