Role of shock structures in transonic fan rotor flutter

A linearized Euler analysis for two-dimensional unsteady flows through harmonically oscillating cascades is presented. A nonlinear Euler analysis, which is based on the implicit time-marching procedure, is also developed and used to validate the shock capturing capabilities of the linearized Euler analysis. Extensive studies on the flutter problem of transonic fans indicate that chordwise motion of the blade is very important to predict the correct flutter boundary at highly loaded conditions. It is also shown that shock structures play a dominant role in determining the aeroelastic response of the cascade and the unsteady load due to shock motion is the main destabilizing source of bending oscillations.