Investigation of mistuning effects on cascade flutter using a coupled method

Effects of frequency mistuming on cascade flutter are studied using a computational method with coupled structural dynamics and aerodynamics. An implicit finite-volume scheme of second-order accuracy is used to solve the unsteady Eider equations. The structural equations with bending and torsional degrees of freedom for a rigid blade profile are integrated in time simultaneously with the flow equations. Investigations are performed on flutter of turbine cascade in bending motion and with alternate mistuming of the structural eigenfrequency. Previous work by an uncoupled method shows a beneficial effect of alternating frequency mistuning on flutter stability. This paper shows that fluid-structure interaction tends to decrease the effective amount of mistuming. There exists a minimum amount of mistuning required to. stabilize the cascade. The same qualitative behavior is shown to exist with a compressor cascade.