Influence of surface grooving methods on steady and dynamic performance of spiral groove gas face seals

In this paper, a structural form called double-sided spiral groove gas face seal is considered. Steady-state performances, such as film load-carrying capacity and film stiffness, of gas face seals with single-sided groove on the stator, single-sided groove on the rotor, and double-sided groove are compared. Introducing axial and angular excitations, coupled with gas lubrication, seal rings vibration, contact mechanics, and instantaneous changes in fluid film thickness, the complete dynamic behavior history is obtained. Two dynamic performance indicators, logarithmic decrement and period valley, are defined. The effects of groove depths and equilibrium film thickness on the dynamic performance of gas face seals with three different surface grooving methods are studied. Combined with the transient sealing performance and film dynamic coefficients, the mechanisms of several typical unstable conditions are analyzed. The results show that the double-sided grooving method has both high gas film load-carrying capacity and gas film stiffness when the equilibrium film thickness is relatively large. In addition, double-sided grooving has both advantages of high gas film damping of single-sided grooving on the stator and high gas film stiffness of single-sided grooving on the rotor, which can ensure stable operation under various operation conditions.