Thermally Induced Dynamics of an Aero-Engine Active Magnetic Bearing–Rotor System

Abstract

Under high-temperature operating conditions in aero-engines, the combined effects of nonuniform heat generation in active magnetic bearing (AMB) coils and ambient thermal loads can lead to nonuniform temperature distributions within the rotor system, thereby generating thermal bending loads and degrading the system’s dynamic stability. To address this issue, a one-way sequential thermo-mechanical analysis framework for an AMB-supported rotor system is developed. The model incorporates thermally induced loads derived from the temperature field, disk unbalance, gravity, and the PID-dependent equivalent stiffness and damping of the AMBs. The governing equations are solved using the Newmark-${\beta}$ method. Based on the proposed model, the dynamic response characteristics of the system under varying bias currents, rotational speeds, and ambient temperatures are systematically investigated. The results show that, under a given thermal condition, increasing the bias current enhances the effective support capability of the AMB, thereby reducing the vibration response. In contrast, increasing the rotational speed progressively amplifies the synchronous vibration response, with a more pronounced increase near the upper end of the investigated speed range. Furthermore, increasing the ambient temperature significantly increases the thermally induced bending excitation, resulting in larger vibration amplitudes. This suggests that, within the investigated operating range, thermal effects strongly affect the system’s dynamic behavior. This study provides a theoretical basis for thermal stability assessment and vibration control of AMB-supported rotor systems operating under high-temperature conditions.