Abstract: Aiming at the problem that the sealing end face of SCO2 dynamic pressure seal was prone to undergo thermoelastic deformation under highparameter working conditions, which affected the sealing performance, a thermo-fluid-solid coupling numerical analysis model of SCO2 dynamic pressure seal was established. The temperature field of the seal ring was solved by considering the viscosity dissipation. The real physical property data of CO2 was used to solve the fluid film pressure field. The temperature field and fluid film pressure were coupled to the seal ring to solve the thermoelastic deformation. The effects of thermal deformation and elastic deformation on the total thermoelastic deformation were studied and compared, the influence of speed, pressure and temperature on the thermoelastic deformation of the sealing end face was analyzed, and a method to reduce the thermoelastic deformation was proposed. The results indicate that SCO2 dynamic pressure seal should reduce the temperature difference of the seal ring at high temperature to reduce the deformation of the end face. High elastic modulus materials should be used to reduce the end face deformation under high pressure. At high speed, the total thermal elastic deformation of the end face can be reduced relying on the mutual restraint relationship between thermal deformation and elastic deformation of the moving ring. The maximum axial clearance of the end face of the seal ring increases linearly with the medium temperature, and decreases linearly with the pressure. The speed makes it first decrease and then increase.

Key words: supercritical carbon dioxide（SCO2）; dynamic pressure sealing; thermoelastic deformation；under high-parameter working conditions