Lubrication Performance and Axial Equilibrium of a Double-Flow Ring Seal Under High Hydrogen Pressure: Response to an Equivalent Oil-Retaining-Ring Outlet Restriction and Hydrogen-Side Oil-Supply Interruption

The lubrication response of a double-flow ring seal in a large hydrogen-cooled generator is investigated under two altered boundaries: an equivalent hydrogen-side outlet restriction representing an oil-retaining ring and the interruption of active hydrogen-side oil supply. The steady model couples Reynolds-film pressure, statistical asperity contact, temperature-dependent oil properties and linear thermoelastic deformation with axial positioning at a prescribed radial eccentricity ratio of 0.30. In the reference case and the field-flow-calibrated equivalent-outlet case, single-end hydrogen-side flow decreases from 387 to 149 L/min and total flow from 426 to 188 L/min. The minimum radial gap remains 0.091 mm, while the maximum radial-surface temperature increases from 91.8 to 95.5 °C. A representative supply-interruption case at hydrogen pressure 0.50 MPa and total thrust clearance 0.41 mm gives 44.6 L/min total flow and a maximum radial-surface temperature of 113 °C. Auxiliary pressure-sweep records show a marked redistribution of flow and thrust clearance among the sampled states around 0.5 MPa. Together, these results illustrate how altered boundaries redistribute pressure forces and axial clearances, and why flow reduction alone is insufficient to assess lubrication performance. The reported magnitudes are case-specific model results, subject to the stated input and validation limitations, rather than general design or safety limits.