Computation of Cascade Flutter with a Coupled Aerodynamic and Structural Model

A computational method for flutter simulation of turbomachinery cascades is presented. The flow through multiple blade passages is calculated using a time-domain approach with coupled aerodynamic and structural models. The unsteady Euler/Navier-Stokes equations are solved in 2D using a second-order implicit scheme with dual time-stepping and a multigrid method. A structural model for the blades is integrated in time together with the flow field. Information between structural and aerodynamic models is exchanged until convergence in each real-time step. The computations are performed on parallel computers using the Message Passing Interface (MPI). Computational results for a cascade are presented and compared with those obtained by the conventional energy method and with experimental and numerical data by other authors. Significant differences are found between the two methods at low mass ratios. Possibilities of nonlinear flutter are demonstrated at certain transonic conditions.