Effect of the 3D layered flow channels within the rotating ring on the steady-state performance of dry gas seals

To address the issue that the sealing performance of traditional hydrodynamic dry gas seal cannot be fully optimized due to the limited space of the sealing face, a novel dry gas seal design with 3D layered flow channels is proposed, featuring layered pump-in or pump-out grooves inside the rotating ring, connected to the end-face hydrodynamic grooves via axial holes. The steady-state performance and flow field distribution of four different flow channel structures, including classic spiral groove seal, layered pump-out groove seal, layered pump-in groove seal, and layered pump-in and pump-out groove seal, are compared and analyzed under various operating conditions. The performance characteristics, applicable operating conditions, and the mechanism of both load-carrying capacity enhancement and leakage controlling of the three-layered flow channel seals are discussed, and optimal values for key structural parameters are obtained. The results show that, compared to the classic spiral groove seal, the opening force of the layered pump-in groove seal can be significantly increased but at the cost of a substantial increase in leakage rate. The layered pump-in and pump-out groove seal, with two to three pump-in and pump-out holes, demonstrates a performance advantage, achieving a 10 % increase in opening force and a 35 % reduction in leakage rate when rotating speed ranges from 10k rpm to 30k rpm, indicating which can offer excellent sealing performance over a wide range of operating conditions. This is mainly attributed to the increase in film pressure within the groove region and the reduction in pressure gradient in the dam region, resulting from the shift of the film pressure peak on the sealing end face from the groove root of the hydrodynamic grooves toward the radial middle of the groove area near the pump-in hole outlet.