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THE development and application of computational uid dynamics (CFD) have made a signifi cant impact on current design of uid machinery. The CFD methods for steady ow analysis can now be routinely used in design on a daily basis. In recent years, there has also been considerable progress made in developing and applying CFD methods to predicting unsteady ow phenomena to improveaerodynamicperformancesandmechanicalintegrityofturbomachines.

It is known that, for periodic unsteady ows, time averaging results in extra stress terms in the time-averaged equations due to nonlinearity, as formulated in the framework by Adamczyk. 1 Under certain conditions, these nonlinear stress terms might affect both the time-averaged aerodynamic performance and aeroelastic characteristics of blades. The nonlinear effect can be naturally included in the solutions by using conventionalnonlinear time-domain …