Abstract:

Based on the study of mechanical face seals with convergent coning or surface micropores, a new type of mechanical seal with both surface micropores and convergent coning was presented.The definitions of face geometric parameters of such a new type of seal were made.Such parameters included the radial taper of the coned face, the width ratio of the coned face to the seal face, and the width ratio of sealing dam to seal face.A theoretical analysis model for controlling fluid film pressure between the two faces of such a seal was set up and was solved with the finite element method.The fluid film pressure profile between the faces was then obtained.Analyses were made about the effect of face geometric parameters on seal performance, such as opening force, leakage and axial film stiffness under low pressure or high pressure of the sealed medium, in which the radial length ratio of micropore zone to face width, circumferential arc length ratio of micropore zone to face circumference, and depth to diameter ratio of a micropore were kept constant.When such a seal was operated under low pressures of the sealed medium, the convergent taper would be beneficial to face opening behavior and the fan-type micropores sector located at the high pressure side of sealing face would be beneficial to sealing ability.When such a seal was operated under high pressures of the sealed medium, the hydrodynamic effect caused by micropores would be beneficial to sealing stability, and the fan-type micropores sector located at the low pressure side would be beneficial to sealing ability.Such a seal would show the best performance when the radial taper varied from 1.5 to 2.5, the width ratio of the conical face to the gross seal face varied from 0.2 to 0.6, and the width ratio of the inner sealing dam to the gross seal face varied from 0.1 to 0.3.