Numerical flutter analysis of turbomachinery bladings based on time-linearized, time-spectral and time-accurate simulations

Within the European research project FUTURE a transonic compressor rotor has been evaluated with respect to its aeroelastic stability. Based on the identical computational mesh different numerical approaches of the DLR flow solver TRACE and the ONERA code elsA are compared in this paper: whereas a time-linearized method based on small time-harmonic perturbations of the steady flow field is chosen in TRACE, elsA uses a non-linear time-domain harmonic balance method in order to determine local aerodynamic work entries and the corresponding global damping values for all inter-blade phase angles (IBPA). Furthermore, nonlinear reference solutions for the critical IBPA range will be provided by both codes using their classical time-marching schemes. In this context the difference in terms of computational effort between the fast linearized or harmonic balance methods and the classical nonlinear techniques shall be highlighted as well.