Performance Degradation and Life Prediction of Gas-Film Floating-Ring Seals Using a Micro–Macro Cross-Scale Friction and Wear Model

Gas-film floating-ring seals are key components in aero-engine bearing-chamber sealing systems, and their reliability is governed by interfacial wear, leakage-channel evolution, and contact-boundary changes. This study develops a micro–macro cross-scale friction and wear model that couples rough-surface contact with seal-clearance evolution. The model describes clearance–near-contact–wear coupling at the primary inner cylindrical interface and pressurized contact–frictional wear–morphology evolution at the secondary axial end face. Friction–wear responses are extracted from a startup–steady-state–shut-down cycle, mapped to the 0–2,000 h degradation process, and validated using test data. A state-space model is incorporated for degradation correction and life prediction, while the effects of pressure difference, rotational speed, and orbit amplitude are examined. The results show that primary wear evolves from local clearance closure and micro-rubbing to circumferential–axial non-uniform opening. Low-pressure-side (LP-side) wear is the main geometric source of effective leakage-clearance enlargement and primary leakage failure. The secondary end face exhibits slow wear and morphology reconstruction under pressurized contact, affecting axial constraint through contact-state and frictional-energy changes. The model reasonably reproduces leakage growth, asymmetric high pressure/low pressure (HP/LP)-side wear, and slow secondary-face wear, with a primary-leakage endpoint error of −3.2%. After state correction, the predicted lives are 4672 h and 20,783 h for the primary leakage and secondary wear limits, respectively. The combined effects of high-pressure difference and large orbit amplitude accelerate clearance closure, LP-side wear opening, and sealing-performance failure.