Segmented annular seals in aircraft engine bearing chambers are susceptible to transient detachment, impact, and wear under extreme operating conditions, which limits their lifespan and reliability. In this work, a transient numerical model coupling discontinuous film flow with the segments is developed, and a convergent micro-texture is proposed to improve stability. This research elucidates the transient failure mechanisms, leakage behavior, and hydrodynamic lift-off characteristics, achieving non-contact stable operation of the seal. The results indicate that under rotor disturbances, the motion of the segments consists of both overall following motion and oscillatory motion. The primary factor causing periodic detachment and impact motion of the segments is the insufficient radial clamping force to resist rotor vibration. Increasing the operating pressure helps maintain seal stability. The leakage rates of both seal structures are mainly influenced by the operating conditions. As the rotational speed and vibration amplitude increase, the segments detach, leading to a significant rise in leakage rate. Under these conditions, the leakage rate decreases with increasing pressure differential. Compared to the conventional structure, the hydrodynamic seal structure exhibits a significantly lower leakage rate, and the gas film reaction force increases by approximately 82%. It can achieve lift-off within the range of 3,000–10,000 r/min and maintain stable non-contact operation at speeds up to 60,000 r/min, with a substantially expanded stability range. These findings provide a theoretical basis for the design and application of segmented annular seals under extreme operating conditions.
