Abstract:The operation status of rotary seal during startup and shutdown operations is unstable,so the lubrication performance of rotary seal greatly influences its reliability.A tribodynamic model of spiral groove rotary seal was developed through coupling hydrodynamic effects,squeeze effects and asperity contact properties.Lubrication characteristics,such as film thickness,asperity bearing force and leakage rate,etc.,were calculated.Transient behaviors of rotary seals during startup and shutdown operations were investigated.The results show that spiral groove rotary seal has fast and stable step response,and the seal ring can return stable operation in a short time.With step changes of speed,hydrodynamic,squeeze and hydrodynamic effects successively become significant factors in lubrication performance of rotary seal.It is also indicated that the circumference friction can improve lubrication performance during startup and shutdown operations.