Hydrodynamic Lubrication in Seals With Cavitation : 4th Report, Lubricating Film between Tilted Flat Faces

Abstract

Axial force and diagonal moment of a radial face seal with tilted flat faces under fixed average film thickness and tilt corresponding to the development of a cavity are calculated. Then, a seal with three degrees of freedom operating under constant axial force and diagonal moment is theoretically analyzed as a practical model of a flexibly mounted mechanical seal, and the angular stiffness is found to be negative. In the experiment on a seal with three degrees of freedom under constant axial force and diagonal moment, a stable film with single cavity could not be realized. Then, tilting angle and average film thickness of seals with reduced degrees of freedom were measured. The principal conclusion is that lubricating film between flat faces is not stable under constant axial force and diagonal moment.