Inward Pumping in Mechanical Face Seals

The hydrodynamic characteristics which produce inward pumping in mechanical face seals are studied. Solutions to Reynolds’ equation for hydrodynamic lubrication are obtained using both the short-bearing approximation and numerical iterative methods. It is found that pumping in face seals results from combined radial eccentricity and misalignment, or one circumferential surface wave. Experimental results confirm the theory.