A Multi-physics Coupling Model Of Hydrostatic Mechanical Seal For Reactor Coolant Pumps And Seal Performance Analysis

Hydrostatic mechanical seal with a convergent coning angle along leakage direction on the end face is a typical mechanical seal type widely used in reactor coolant pump(RCP). Work safety and stability of RCP in a long cycle time greatly depends on the stability and reliability of the seal system, which is difficult to design. At present, related technology of the seal products abroad is already robust, while in China the ability on designing and manufacturing isn’t existed. Under the super-high pressure working conditions, the thermo-mechanical coupled deformation of seal rings end faces and hydrostatic lubrication effect between the faces significantly influences the seal performance. Nonlinear contact reaction among seal components baffles the deformation prediction of seal rings end faces. In this dissertation, to solve this problem, the following work is completed in expectation of offering technical suggestions for seal design.Firstly, the two-dimensional axisymmetric finite element models of hydrostatic mechanical seal components was established by considering the nonlinear contact between seal components (seal rings, seal seats, clamping rings, O-rings, etc). The nonlinear boundary constrained condition of stator and stator under different pressure was obtained. This lay the foundation for analysis and prediction of the seal performance.Secondly, this paper take the seal rings and the lubrication film as the research object, considering the effect of temperature and pressure on viscosity of the fluid film and the thermo-mechanical deformation of the end faces, a two-dimensional axisymmetric multi-physics coupling model is established. The boundary constrained condition gained above is used. The finite difference method for lubrication equation, energy equation and heat equation and the finite element method for deformation equation are used to decouple the mathematical model by iterative algorithm. Finally, based on the multi-physics coupling model, the parameterized research is conducted to analyzing the seal performance, including the effect of the positon of the O-ring on the sea ring bottom, the screw force, balance ratio, the coning angle and the seal pressure etc. Results show that appropriate boundary constrained condition has significant effect on seal performance. The majority of the friction heat produced by the viscous shear effect in the end face is taken away by leaking fluid. Pressurized deformation has larger effect on seal performance than thermal deformation. The effects of bolt preload of clamp, main geometric parameters and seal pressure on seal performance have been analyzed. The conclusion can be used to guide seal structure design.