Three-Body Two-Way Fluid-Solid Coupling Model and End Face Mechanical Deformation Law of High Pressure Dry Gas Seal

A three-body two-way fluid-solid coupling model of dry gas seal was proposed by comprehensively considering the three key factors, including fluid film pressure, seal ring structure and seal ring seat force, that affected the mechanical deformation of seal ring end face and their interaction. Taking the classical high-pressure dry gas seal structure as the research object, the film pressure was obtained by solving the Reynolds equation with turbulence, the deformation of seal ring and the stress and strain of the spring energized seal ring was solved by the commercial software ANSYS. The deformation law of seal ring end face under different structural parameters and operating conditions was studied. The effects of three fluid-solid coupling models and flow model, the axial thickness of the sealing ring and the radial position of the auxiliary seal on the deformation of the sealing ring end face and steady-state performance were compared and analyzed, and the optimal value range of the above-mentioned structural parameters was obtained. The results showed that compared with the three-body two-way fluid-solid coupling model of dry gas seal considering the interaction of 'fluid film-sealing ring-ring seat', the three-body one-way model which ignoring the interaction between the fluid film and the sealing ring would make the end face force deformation of the sealing rings larger, while the two-body two-way model which ignoring the ring seat force would make them significantly smaller. The average film thickness and leakage rate obtained by the three-body one-way model and the two-body two-way model were significantly smaller, and the predicted leakage rate was 38.5% and 33.5% smaller, respectively. The selection of turbulent and laminar flow pattern model had little effect on the shape of sealing gap, but the predicted value of laminar flow model for outlet blocking pressure was higher, which would make the average film thickness and leakage rate higher when the pressure was low (8 MPa), and make the average film thickness and leakage rate significantly lower when the pressure was high (16 MPa), and the relative errors reached 38% and 15%, respectively. Increasing the axial thickness of the rotating ring and the radial position of the stationary ring auxiliary seal only changed the deformation of the corresponding seal ring end face without affecting the deformation shape, and made the opening force and leakage rate monotonically decreased. Increasing the axial thickness of the stationary ring and the radial position of the auxiliary seal of the rotating ring would significantly change the deformation direction of the corresponding seal ring, and the opening force and leakage rate would increase monotonously, and by reasonably combining with the axial thickness of the rotating ring and the radial position of the auxiliary seal of the static ring, the goal of lower leakage rate, near parallel gap and suitable operating film thickness could be achieved.