Computation of mistuning effects on cascade flutter

A computational method is described for predicting Butter of turbomachinery cascades with mistuned blades. The method solves the unsteady Euler/Navier -Stokes equations for multiple-blade passages on a parallel computer using the message passing interface. A secund-order implicit scheme with dual tim e-stepping and multigrid is used. Each individual blade is capable of movin g with its own independent frequeucy and phase angle, thus modeling a casca de with mistuned blades. Flutter predictions are performed through the ener gy method, Both phase-angle and frequency mistuning are studied, It is foun d that phase-angle mistuning has little effect on stability, whereas freque ncy mistuning significantly changes the aerodynamic damping, The important effect of frequency mistuning is to average out the aerodynamic damping of the tuned blade row over the whole range of interblade phase angles (IBPA). If a tuned blade row is stable over most of the IBPA range, the blades can be stabilized fur the complete IBPA range through appropriate frequency mi stuning.