Effects Analysis of Thermo-elastic Deformation on the Performance of Hydrostatic Mechanical Seals in Reactor Coolant Pumps

Abstract

The thermo-elastic deformation of a hydrostatic mechanical seal used in reactor coolant pumps plays an important role in sealing performance because of the operations at high-pressure,high-speed and in a wide temperature range.A steady heat transfer model is established for such a hydrostatic face seal with convergence gap.Considering the variation of dynamic viscosity along with that of fluid pressure and temperature,the governing equations of fluid film pressure and seal ring temperature are set up and solved by using finite difference method.The thermo-elastic deformation is solved by using finite element method.The thermal-fluid-solid coupled analyses are carried out.The effects of thermo-elastic deformation on sealing performance are studied.The variations of face temperature,thermal-elastic deformation,and fluid film thickness with operating conditions are presented.It is found that the amount of elastic deformation is greater than that of thermal deformation under the considered conditions.A convergence gap between two sealing faces from the outer radius to inner radius is formed by thermo-elastic deformation,which results in the increases of opening force,leakage rate and liquid film stiffness.The higher the angular speed of rotating ring is,the greater the fluid temperature rise,the more obvious the face thermal deformation,and the greater the leakage rate will be.A lower temperature of the inlet fluid will lead to a greater effect of temperature on viscosity.A higher pressure of the inlet fluid will result in the increases of thermo-elastic deformation and the balancing film thickness.