Influence of separation, collision and friction of rotating ring in sleeve on vibration characteristics of gas face seals

Purpose This study aims to understand how the assembly of rotating ring affects the axial forced vibration of gas face seals. Design/methodology/approach A three-mass kinematic model is established to investigate the axial movement of the rotating ring with bilateral constraints. The separation, collision and frictional sliding of the rotating ring in sleeve are discussed under rotor excitation. The effects of operating parameters and O-ring dynamic characteristics on the separation degree and film thickness disturbance are analyzed. A dimensionless axial characteristic force is defined to determine the critical conditions for the occurrence of separation. Several effective methods to eliminate the separation are proposed based on the adjustment of typical installation parameters. Findings Under rotor excitation, there may be two collisions between the rotating ring and the sleeve surfaces in one excitation period. This will cause self-excited vibration of the fluid film, increasing the risk of seal failure. The separation and collision can be prevented by increasing the equilibrium ratio, the installation radius of the O-ring on the outer surface of the rotating ring and the friction in the sleeve. Originality/value The results develop the modeling of multibody dynamics of gas face seals, enabling more accurate prediction of vibration characteristics.