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

Abstract

Forced response is one of the aeroelastic problems which lead to the blade damage. The energy method based on the hypothesis of a conventional travelling wave model and direct numerical simulation are used usually to analyze the problem. However, energy method cannot cover the fluid-structure coupling effect, while numerical simulation needs large computational cost. A rapid method, based on the reduced order model (ROM), is developed to analyze the forced response of the rotor blades. The unsteady aerodynamic force acting on blades is divided into two parts according to the source. One part is due to the blade vibration. An unsteady aerodynamic force model is built to simulate it and then an aeroelastic model is built by coupling the structural equation. The other part is due to rotor-stator interaction (RSI), which is regarded as the excitation of the aeroelastic model. Then the forced response of the rotor blade rows is transferred to calculate the response of the aeroelastic model under the RSI excitation, which requires one to two orders of magnitude less computational time than direct numerical method and could study the effect of the structural parameters conveniently. Results show that the effect of fluid-structure coupling is crucial to the low-mass-ratio structure. Besides, the structural frequency is not exactly coincident with the excitation frequency when the response amplitude reaches its peak.