Hydrodynamic Lubrication in Seals With Cavitation : 3rd Report, Effect of Coning in Radial Face Seal

Abstract

Hydrodynamic lubricating film between a saddle shaped face and a coned face with cavities is theoretically analyzed by a universal Reynolds equation applied to the continuous film and the cavities. In the experiment, the minimum film thickness and the leakage flow rate of a seal with manually controlled cavities are measured with the conclusions reached as follows : (1) Though the minimum film thickness is reduced, the axial stiffness of the film scarcely increases. (2) In a coned seal, when the outside pressure is higher than the inside one, the film thickness increases remarkably due to the outside pressure. (3) In a coned seal with cavitation, outward pumping is generated, and a high flow rate results from a large axial force and coned angle. (4) When the outside pressure is higher, good lubrication is possible with almost zero leakage if the inward flow due to the pressure difference is balanced with the outward pumping.