Lubrication Characteristics of Spiral Groove Mechanical Seals during Transient Start-up

A mathematical model of lubrication characteristics and sealing performance in spiral groove mechanical seals during transient start-up was established,which included the average Reynolds equation with flow factors, contact factor and JFO(Jakobsson-Floberg-Olsson) (mass conserving) cavitation boundary, elastic-plastic asperity peak contact equation as well as the equations of axial dynamics model. Furthermore, the influences of different working conditions and structural parameters on lubricate regime transformation were compared. Results show that fluid bearing capacity and film thickness increase while the asperity peak contact force gradually decreases to zero during acceleration periods. Mixed lubrication regimes have larger film stiffness and more obvious oscillation amplitude compared with hydrodynamic lubrication regimes. A distinct mutation of axial speed appears when reaching separation speed. The smaller accelerated speed may achieve hydrodynamic lubrication regime at low speed affected by squeezing effect. Both higher outer pressure and lower inner pressure are beneficial to the transformation of lubrication regimes. The separation speed ascends at first and then descends with the increment of groove number. The decrease of spiral angle, groove depth and the increase of groove width ratio play an effective role in the ability of lubrication regime transformation. © 2020, China Mechanical Engineering Magazine Office. All right reserved.