The Effect of High Speed Airflow Lubrication on Hydrodynamic Properties of Inclined-Dimples Face Seals

The hydrodynamic properties of high speed airflow lubrication of inclined-ellipse-dimples face seals were theoretically studied with consideration of choked flow effect and entrance pressure loss. Influence of the choked flow effect on the sealing parameters, opening force and leakage rate, was numerically analyzed under different operating conditions of seal pressure and rotational speed. Meanwhile, influence of geometric parameters (e.g. seal face width) and texturing parameters (e.g. slender ratio, inclination angle, dimple depth and dimple area rate) were also discussed. The results show that the entrance pressure loss led to drop of the inlet pressure while the choked flow effect increased the exit pressure, which resulted in the decrease of the opening force and the leakage rate. The choked flow effect increased with increasing rotational speed and seal pressure. Compared to the values under the coercive boundary, the opening force decreased more than 5% in the cases of the seal pressure 10 MPa and the rotational speed 50 000 r/min, and the leakage rate decreased more than 62%. In order to obtain better hydrodynamic opening force, 2~4 μm dimple depth and 20~40° dimple inclination angle were recommended.