Mechanism and Performance of End Face Seal of Rayleigh Steps and Annular Grooves

Lubrication theory model of mechanical seal end face of Rayleigh steps and annular grooves was established based on the JFO cavitation boundary conditions. The Reynolds control equation was solved by the finite element method. Pressure, density ratio and streamline distribution of the fluid film were obtained, and sealing mechanism and sealing performance were analyzed. The results show that the combination of the shallow annular groove of the inner diameter side and the deep annular groove in the middle of the sealing surface can cause a reasonable cavitation phenomenon, which can achieve the purpose of reducing leakage. The deep annular groove in the middle of sealing surface, the isolated zone of the high pressure area of the outer diameter side and the low one of the inner diameter side, led to the result that pressure distribution of the low pressure area was almost not influenced by that of the high pressure area. When the sealing fluid entered the shallow annular groove, the sealing gap suddenly diverged and became larger, which led to lower pressure than the saturated vapor pressure at the operating temperature. The liquid film in the whole shallow annular groove cavitated and caused zero leakage or a large amount of backflow phenomenon. A good bearing capacity was provided by the Rayleigh steps at the outer diameter side and the non-contact state of the end faces was achieved. The combination of Rayleigh steps and annular grooves rendered the mechanical seal excellent comprehensive performance.