An efficient coupled method of cascade flutter analysis by using CFD technique

As direct numerical simulation of fluid/structure interaction of entire blade row is computation-intensive and time-consuming, this paper presents a reduced order model (ROM)-based coupling method which takes fluid/structure coupling effect into account and provides a significant increase in efficiency of flutter analysis of turbomachinery. This method computes unsteady aerodynamic forces of several blades in time domain by computational fluid dynamics (CFD) technique, and then constructs the reduced order aerodynamic model of entire vibrating cascade with system identification and several assumptions. And finally, this method establishes the aeroelastic model of entire cascade by coupling the reduced order aerodynamic mode with cascade structural dynamic equation in state-space form. Flutter characteristics of STCF4 (Standard Test Configuration 4) and NASA Rotor67 cascade are analyzed by solving eigenvalues of the aeroelastic model. The accuracy of this method is validated by comparing the results of direct computational fluid dynamics/computational structural dynamics (CFD/CSD) coupling method and uncoupled method. The ROM-based coupling method improves computational efficiency by nearly two orders of magnitude compared to direct CFD/CSD coupling method. Besides, this method provides an effective and reliable approach for parameter analysis, mistuning and multi-mode coupling calculation of turbomachinery.