Comparison and analysis of the performance of a spiral groove mechanical seal subjected to phase change with different sealing media

Abstract

The goal of this research is to investigate the impact of four kinds of easily vaporized sealing media(liquid hydrogen, liquid oxygen, liquid nitrogen and water) on phase change and sealing characteristics of a spiral groove mechanical seal(SGMS). Based on homogeneous flow assumption, a dynamic continuous boiling model is developed taking into account phase change of fluid film. With fluid pressure and fluid enthalpy as primitive variables, the properties of single-phase fluid and mixture fluid can be obtained by REFPROP software. The influence of the sealing medium on phase state stability criterion, steady-state and dynamic performances, and geometric structure parameter optimization is investigated. The findings reveal that dynamic viscosity is the key physical parameter of the sealing medium, affecting the seal stability and the phenomenon of phase change of an SGMS. The sealing medium with a high dynamic viscosity may obviously block the phenomenon of vaporization, which is advantageous in delaying the process of phase change and shortening the temperature range of quasi-vapor phase state in which an SGMS is unstable. The trends of steady-state and dynamic performances of an SGMS undergoing phase transition are identical for any type of easily vaporized fluid indicated in this work as a sealing medium. Taking into account both steady-state and dynamic performances, and independent of the type of sealing medium used, the best range of groove-to-dam ratio of an SGMS undergoing phase change is 0.5 < γ < 1.5.