Analytical study of pressure balancing in gas film seals.

Proper pressure balancing of gas film seals requires knowledge of the pressure profile load factor (load factor) values for a given set of design conditions. In this study, the load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however, the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.