Influential Analysis of Sealing Length on Vibration Response Characteristics of Bearing Casing Systems in Aircraft Engine Rotors

To analyze the impact of the sealing length of labyrinth seals on the vibration characteristics and operational reliability of aircraft engine rotor systems, a dynamic model of the rotor-bearing-casing system was established based on Muzynska seal force model. The model considered the effects of supporting bearing forces, coupling misalignment forces, nonlinear oil film forces, and rub-impact forces. The system’s vibration response characteristics were obtained by applying the fourth-order Runge–Kutta method for different seal lengths. The results indicate that the seal-induced dynamic forces have a minor effect at low speeds. As the speed increases, the system transitions from chaotic motion to quasi-periodic or periodic motion under the influence of seal-induced forces. With an increase in seal length, the system’s operation becomes more stable, but the additional mass from the seal length also leads to chaotic responses, expanding the region of chaotic behavior. The coupling fault characteristics of the rotor system can be analyzed by observing and extracting signals from the casing. This research provides technical references for the diagnosis of seal-induced vibration fault and structural optimization of rotor systems.