Evaluation of Fast Numerical Methods for Turbomachinery Blade Flutter Analysis

Different numerical methods for blade flutter analysis were employed to evaluate the flutter stability of a typical low pressure turbine bladerow tested in the context of the European research project FUTURE. This aeroelastic testcase was extensively studied during the project by a large number of partners, becoming a suitable benchmark to compare numerical techniques for flutter prediction. In this study, two different uncoupled aeroelastic methods (time-linearized and non-linear) were used to assess the flutter stability. The results highlight a very good agreement between the two approaches even when the non-linear code was applied with some approximation strategies (non viscous endwalls and wall functions). The two analyzed bladerow configurations (cantilever and interlock) show unstable and stable flutter behavior respectively, and the numerical flutter predictions are in agreement with the experimental evidences obtained during the project. Finally the two methods were also evaluated in terms of computational time. This is due to the fact that flutter assessment methods are more and more used during the turbomachinery design, even during the bladerow optimization.