Variable-speed aircraft engines require the power turbine rotor to operate stably within a wide range of output speeds, posing a challenge for rotor vibration reduction design. Non-concentric squeeze film dampers (NCSFDs) have been widely used in rotor vibration reduction design due to their simple structure. However, comprehensive research on the matching and applicability of NCSFDs under varying operating speeds is lacking. Therefore, this paper investigates the influence of oil film radial clearances on the dynamic characteristics of a variable-speed rotor system with an NCSFD, examining its suitability across variable speeds. This study introduces the principle of equivalent rotor dynamics similarity design, demonstrating good consistency between simulated and real rotor dynamic characteristics, with a radial clearance of 0.10 mm being deemed optimal. The vibration response variation in the rotor at a fixed speed within the range of 0.51 n to 1.0 n does not exceed 4 μm, and the vibration acceleration variation does not exceed 0.04 g, indicating a wide, stable operating speed range. This study can be helpful for the engineering design and vibration reduction design of variable-speed rotors in aircraft engines.

This study investigates the stiffness characteristics of elastic ring supports and the dynamic response of aero-engine rotor systems. First, comparative analysis demonstrates that the finite element model provides higher accuracy in predicting the stiffness of the elastic ring compared to traditional analytical methods, with the experimental error controlled within 5%. Grid independence verification further reveals that the mesh density in the boss region is a critical factor determining the accuracy of stiffness calculations. On this basis, the influence mechanism of contact states on stiffness characteristics was deeply explored; it was found that the transition between frictional and bonded contact states can lead to a stiffness deviation of up to 46.8%. Furthermore, quantitative analysis of manufacturing tolerances indicates that the thickness deviation of the boss should be strictly controlled within 0.02 mm to ensure the stability of support performance. Finally, a dynamic model of the rotor system developed using two-dimensional beam elements was fully validated against experimental data, with a calculation error of only 2%. The results of this study provide an important reference for the precise design and stiffness evaluation of elastic ring supports, as well as the engineering testing of rotor system dynamic characteristics.

Finite element method was used to establish the calculation model of the dynamic characteristics of the simulated power turbine rotor, and the dynamic characteristics of the rotor were systematically calculated and analysed. The variation law of the first three stages critical speeds of the rotor with the supporting stiffness and the mass of each disk were revealed. The dynamic characteristics test of the simulated power turbine rotor in the full speed range was completed, and the calculation results and test results were compared and analysed. The results show that the calculation model reflects the dynamic characteristics of the rotor well, and the rationality of the rotor structure design, supporting layout and critical speed distribution were verified. The study provides a theoretical basis for the adjustment of critical speed based on the supporting stiffness and disk’s mass, it also provides technical reference for the real rotor structure design and test.