Forced Response Analysis of Rotor Blades with the Mode-Based Aeroelastic Model

Abstract

Forced response is a common aeroelastic problem which can lead to blade damage. The computational fluid dynamics/computational structural dynamics (CFD/CSD) simulation is the most accurate numerical method to analyze the problem but needs large computational cost. By constructing a reduced-order model (ROM) of the aeroelastic system, this paper proposes a high-efficiency and accuracy method for forced response analysis. First, the unsteady aerodynamic force acting on blades is divided into two parts depending on the source. One part can be attributed to the blade vibration, which is modeled using a ROM. The aeroelastic model is then built by coupling the ROM with the mode-based structural equation. The other part is due to rotor-stator interaction (RSI), which is regarded as the excitation of the aeroelastic model. Then, the response of the aeroelastic model is calculated using both the time domain method and the frequency domain method to obtain the forced displacement response and stress response of the rotor blade rows. Finally, the proposed method is examined on the forced response analysis of the second-stage rotor blades of NASA67 due to the RSI of the first-stage stator. Results show that the maximum vibration amplitude of the rotor blades is not acquired at the synchronized point where the structural natural frequency equals the excitation frequency. The efficiency of the ROM method is increased by around 1,799.6 times compared with the CFD/CSD method. According to the stress analysis, it is found that the maximum stress of the blade is about 80 MPa near the stall point.