Advanced Dynamic Model Development of Dry Gas Seal

Dynamic processes of dry gas seal operation are investigated in this paper. Joint consideration of three models is used to determine stiffness and damping properties of the gas film. There are a two-mass dynamic model, hydraulic model (to determine pressure distribution in the sealing gap) and spiral-grooves model (to determine seal gap). Lifting force of the seal is analyzed under conditions of axial rotor oscillations. For this purpose, single-mass models (varying degrees of complexity) “rotating ring - rotor” are created. An analytical solution in the first approximation can provide the determination of dangerous oscillation levels. The phenomenon of separation of rotating ring and sleeve's face on a rotor is investigated. Causes of this phenomenon are analyzed. Motion characteristics of the rotating ring are calculated for two cases. The first one directly deals with the separation process; the second one examines the impact of inner sleeve on the seal operation. Analytical three-mass model of the seal is created to determine the dynamic characteristics for the case of separation. Results from analytical solution are compared with the results from numerical simulations.