Forced response analysis of the rotor blade rows with the ROM-based aeroelastic model

Abstract

A rapid method, based on the reduced order model (ROM), is developed to analyze the forced response of the rotor due to the rotor-stator interaction. The unsteady aerodynamic force acting on blades is divided into two parts according to the source. One part is due to the rotor-stator interaction, while the other is due to the blade vibration. The aerodynamic forces due to the rotor-stator interaction is regarded as excitation, while an unsteady aerodynamic force model is built to calculate the unsteady aerodynamic force by the blade vibration. Then an aeroelastic model is built via coupling the structural equation with the unsteady aerodynamic force model. The aeroelastic model is calculated with the excitation of the aerodynamic forces due to the rotor-stator interaction. The forced response for the 50% height of the NASA67 secondstage rotor is analyzed by the CFD/CSD method, the ROM method and the energy method via time domain method respectively. Compared with the energy method, the relative error of the resonant amplitude is fallen from 12.5% to 0.06% by ROM method, while the efficiency is improved by 46.36 times as compared with the CFD/CSD method. In order to discuss the influence of structural parameters, the forced response analysis is conducted by the ROM method with various mass ratios and structural frequencies. It illustrates that the effect of fluid-structure coupling is crucial to the low-massratio structure. Furthermore, the structural frequency is not exactly coincident with the excitation frequency when the response amplitude reaches its peak.