Theoretical Research On Thermoelastohydrodynamic Effects Of Hydrodynamic Mechanical Seals In Reactor Coolant Pumps

As the key technology of reactor coolant pumps, the stability and reliability of mechanical face seal have the direct influence on pump’s safe operation. The high pressure causes mechanical deformation, and the viscous shear friction heat not only causes thermal deformation but also changes the face seal temperature field. Too high temperature reduces the viscosity of liquid film, large face deformation will not only lead to leakage rate increasing, but also induce vaporization, which will largely affect seal performances. Therefore, it is of profound guiding significance to explore the hear transfer law of seal system and predict face deformation for the improvement of service lives and the development of new products of mechanical seals.Firstly, the research is focused on semicircle deep grooves hydrodynamic single-stage mechanical seal. Taken the temperature-viscosity effect into consideration, three-dimensional steady heat-fluid-solid coupling finite element model was established. The governing equations on thermoelastohydrodynamic lubrication were also established based on the simplified energy equation. Secondly, in order to get convection heat transfer coefficients, a two-dimensional axisymmetric conjugate heat transfer finite element model, consisting of fluid domain and seal domain, was also developed. Based on those equations mentioned above, the heat transfer law of seal system and the effect of operation parameters on temperature field were analyzed without considering face deformations. Finally, according to thermoelastic deformation theory and lubricating and sealing technology, temperature field was studied with the deformations considered; the influence of operation parameters and deep grooves structure parameters on seal face temperature and seal performances were also studied.Results showed that convection heat transfer coefficients gotten by conjugate heat transfer preferably reflect the changing rules of convection. When considering face elastic deformations, circular waviness of face and unevenness of temperature caused by deep grooves increase and become even larger with the increase of rotation velocity, pressure and grooves structure size; meanwhile, the friction coefficient decreases, which shows a significant impact on seal performances.