Simulation Method of Rotor Dynamic Characteristics Considering Temperature Distribution and Aerodynamic Load

Abstract

Abstract When operating in a high-temperature and high-pressure environment, the high-speed rotor systems of aero-engines are inevitably subjected to thermal and aerodynamic loads. However, conventional simulations and experiments of rotor dynamics did not consider temperature distribution and aerodynamic load. Therefore, it’s necessary to investigate the influence mechanism of temperature distribution and aerodynamic loads on rotor dynamics. Using polynomial function fitting for the continuously various parameters in elements, combined with the temperature distribution, the axial distribution of physical parameters in shaft elements was established. The stiffness coefficient matrix considering temperature load was derived based on Timoshenko beam theory. By introducing the tension (compression) potential energy, the additional stiffness coefficient matrix was derived from Lagrange equation. Using state-space vector method, the differential equations of motion for rotor-support system were solved, and dynamic characteristics of rotor system subjected to temperature distribution and aerodynamic force were analyzed. The simulation method was verified with a typical fan rotor under the maximum operating condition. The results indicate that the rotor dynamic behavior is more sensitive to temperature distribution than aerodynamic load when operating in the temperature range of 40∼190°C. And the decrease of first two critical speeds is mainly caused by thermal load. Due to the relatively low temperature, the first-order critical speed of fan rotor considering the additional load is reduced slightly, while the second-order one is decreased by 3.42%. When a mass unbalance of 500 g·mm is located at the first disk, the resonant amplitude of unbalance response rises slightly (0.25%) with additional load. If such amount of unbalance is located at the third disk, the peak amplitude is increased by 1.28%. In addition, such a simulation method could be extended to core engines or even dual- or triple-rotor engines with higher temperature and aerodynamic load, where the dynamic characteristics and unbalance responses are expected to be significantly affected.