A Bi-Directional Gas Face Seal

Abstract

The purpose of this paper is to present, analyze and optimize the geometry of the bi-directional radial groove film-riding gas seal (1). Performance is both hydrodynamic and hydrostatic and is independent of rotational direction. The hydrodynamic geometry is an equally spaced set of alternating lands and grooves. The typical operating gap of the seal is very small and a laminar viscous flow field governed by Reynolds equation is assumed. A parametric study of the controlling equations shows that five dimensionless geometric parameters, the gas compressibility number and the pressure ratio fully define the problem. A two-dimensional steady-state analysis was performed to characterize film stiffness and leakage as a function of the governing parameters. Optimum geometry is identified in terms of the five dimensionless governing parameters. The bi-directional radial groove gas seal generates a significant hydrodynamic pressure field, which makes it suitable for numerous sealing applications.