Abstract: At high speeds, substantial viscous heat is generated in the lubricating fluid of end clearance by the strong shearing action of the rotor. The hydrodynamic lubrication (HD) and thermal hydrodynamic lubrication (THD) characteristics of the annular fluid-spiral groove composite mechanical seal (ASG) model are numerically analyzed. The influence mechanism of liquid film viscous thermal effects on mechanical seal performance is clarified, and the influence laws of ASG geometric parameters on seal performance are investigated. The results indicate that similar pressure distributions are presented by HD and THD models, whereas the hydrodynamic pressure effect of the ASG model is weakened when viscous thermal effects are considered. A significantly higher temperature is observed in the non-grooved zone of the stator end face compared with the grooved zone, while a slightly lower temperature is detected on the rotor end face than on the stator end face. The temperatures of the liquid film, rotor and stator are all gradually increased from the outer diameter to the inner diameter. Under various geometric parameters and working conditions, lower predicted liquid film opening force and friction coefficient values are obtained by the THD model than by the HD model. Rotor temperature is raised with the increase of rotational speed. Larger groove width ratio, groove dam ratio and sealing gap are conducive to temperature reduction but result in an increased leakage rate. Effective temperature reduction cannot be achieved by simply increasing groove depth, and an optimal groove depth is available for thermal management optimization.

Key words: mechanical seal, thermohydrodynamic lubrication, annular groove, spiral groove