Leakage Prediction in Mechanical Seals Under Hydrostatic Operating Condition

Abstract

ABSTRACT This paper considers leakage in mechanical seals under hydrostatic operating condition. A contact model based on the Greenwood and Williamson contact of rough surfaces is developed for treating problems involving mechanical seals in which both the micron scale roughness of the seal face and its macro scale profile are used to obtain either a closed-form equation or a nonlinear equation relating mean plane separation to the mass flow rate. The equations involve the micron scale geometry of the rough surfaces and physical parameter of the seal and carriage. Under hydrostatic condition, it is shown that there is an approximate closed-form solution in which mass flow rate in terms of the mean plane separation, or alternatively, the mean plane separation in terms of the leakage mass flow rate is found. Equations pertaining to leakage in nominally flat seal macro profile is considered and closed form equation relating to leakage flow rate to pressure difference is obtained that contain macro and micron geometries of the seal. INTRODUCTION Mechanical seals are among important machine components and play a critical load when containment of lubricant is necessary in machinery. There is extensive literature In this paper we develop approximate equations relating contact force and mean plane separation. Using the closedform equations, we consider the leakage in flat face mechanical seals and obtain the closed form equations relating leakage mass flow rate as a function of surface topography, fluid pressure and macro geometry of a seal