Performance Evaluation of Bidirectional Dry Gas Seals with Special Groove Geometry

ABSTRACT

There are a very few studies of bidirectional gas seals, particularly those with certain profiles used in the industry. A parametric study of the performance of bidirectional dry gas seals under a set of operating conditions is presented. The expounded approaches use solution of 3D Navier-Stokes momentum and continuity equations for various forms of grooved gas seals, particularly for the trapezoidal shape variety for which there has been a particular dearth of in-depth analyses. It is shown that such groove geometries enhance the load-carrying capacity of the seal through increased hydrodynamic lift. This is as the result of enhanced localized wedge flow, particularly with a reduced seal gap. Therefore, there is the opportunity of gap minimization while reducing leakage rate and power loss. For given operating loading, kinematic and thermal conditions, as well as seal geometry and topography, the operating minimum film thickness may be considered the main design parameter.

KEYWORDS:

• Dry grooved gas seal
• bidirectional
• hydrodynamic lift
• power loss
• leakage

Acknowledgements

The first author wishes to express her gratitude to the Chinese Scholarship Council (CSC) for providing her with the opportunity to carry out this research at Loughborough University, UK. Thanks are also due to John Crane Ltd. for providing representative data and technical support.