Investigation of Mistuning Effects on Cascade Flutter Using a Coupled Method

Abstract

Effects of frequency mistuning 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 Euler 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 a turbine cascade in bending motion and with alternate mistuning 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 mistuning. There exists a minimum amount of mistuning required to stabilize the cascade. The same qualitative behavior is shown to exist with a compressor cascade.