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.