The spherical mechanical seal which can automatically adjust the contact state of sealing surfaces is proposed to replace the frequently-used plane mechanical seal in order to solve the problems that when a marine stern shaft is bent with shafting misalignment and stern bearing wear factors, etc., the sealing properties of a plane mechanical seal is declined with the increase of both contact pressure and temperature of sealing surface. The sealing properties of a spherical mechanical seal is directly influenced by the sealing structure size such as sealing spherical radius, the distance between stator and rotary ring seats as well as both inner and outer diameters of stator ring. The thermal-structure coupling model of the spherical mechanical seal in underwater vehicles is built with the ANSYS finite element method, and the influence of structure size on the sealing performances of the spherical mechanical seal is discussed. The study results show that as spherical radius is increased, the contact region of spherical sealing surfaces is decreased and the opening region is expanded, and the highest temperature and maximum contact pressure on the spherical sealing surfaces are raised. As the inner or outer diameter of the stator ring is increased, the maximum contact pressure of the former is raised, and one of the latter is declined, but the highest temperatures of both on sealing surfaces are enhanced linearly. When the distance between static and rotary ring seats is increased, the highest temperature of sealing surface and maximum contact pressure are increased in a nonlinear way. These conclusions are of important theoretical significance and engineering application value for the structural optimization of spherical mechanical seals in vessels, particularly of underwater vehicles.
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Reference: Zhou, X.; et al (2016). Research on Sealing Properties and Its Influence Factors of Spherical Mechanical Seal Based on ANSYS., DOI: 10.2174/1874155X01610010160