Research on the mechanism of suppressing flutter of cascade with frequency mistuning

Abstract

Flutter is an aero-elastic problem that must be avoided in aero-engines. As the most effective method to suppress flutter, frequency mistuning has been widely concerned and studied. However the current understanding of the mechanism of frequency mistuning to suppress flutter is limited, so the exploration of its mechanism is of great significance in practical engineering. In this paper, the influence coefficient method is used to study the effect of frequency mistuning forms and frequency difference on the aerodynamic damping coefficient and cumulative work of the mistuned cascade, and the limitation of the definition of the aerodynamic damping coefficient of the mistuned cascade is pointed out. Besides the mechanism of frequency mistuning to suppress flutter is explored. In addition, this paper also combines the resonance theory to study the method of calculating the minimum frequency difference to stablize the cascade. The results show that the frequency mistuning suppresses flutter by reducing the aerodynamic coupling between the blades in the cascade, and the frequency mistuning of the adjacent blade on the suction surface of the reference blade plays a decisive role in the aero-elastic stability of the reference blade. Moreover, the greater the frequency difference, the smaller the amplitude of the reference blade cumulative work, the better the effect of frequency mistuning on improving the aero-elastic stability of the cascade. Furthermore, it is feasible to use the reference blade resonance band to calculate the minimum frequency difference to stablize the cascade.