Theoretical Study On The Performance Of Mechanical Seals With Deep Grooves Used In Reactor Coolant Pump

As one of the key parts of a reactor coolant pump(RCP), mechanical seal can strongly influence the pump's stability and security. A hydrodynamic face seal with deep grooves was usually used in a RCP. The sealing performance, wear behavior and principle of such a seal used at high pressure was studied in this thesis. The results are valuable to our country to develop independently such high-performance seals.First of all, the Reynolds equations was employed. Then a mathematical model was developed to analysis the performance of circular arc groove hydrodynamic mechanical seal, which based on lubrication theory. Then the finite element method(FEM) was used to solve the governing equations for circular arc deep groove hydrodynamic seal. It is suggested that the dynamic effect of deep groove mechanical seal is unobvious when the face's deformations is neglected. The static effect, which is more obvious than shallow groove mechanical seal, will help to open the mechanical face when starting the pump and then the velocity is small.Secondly, three dimensional numerical model of mechanical seal was built to analysis the deformations of the seal rings, both stator and rotor. A parameter named the ratio of elastic modulus and pressure of outside surrounding was introduced as the criterion to analysis the effect of deformation. The coupling effect of pressure distribution and face deformations was studied. It is suggest that it is obviously different when take the deformation into account. The deformation, which can be divided into radial taper deformation and circumferential wave deformation, can increase the stiffness and the ratio of stiffness and leakage which is benefit for stability.Lastly, an abrasion model was developed to study the seal's performance when it is wore. The leakage trend was calculated after wore. It is suggested that one can judge the seal condition by indicating the leakage rate, thus it can be managed previously to prevent urgent shutdown, which may involve great losses.