The prediction of resonance amplitudes due to stator-rotor interactions is still an important task within the design process of turbomachinery bladings.
In this paper the stator-rotor interaction of a compressor stage which consists of an inlet guide vane and a rotor blade is studied with a non-linear and a linearized CFD code. First, a quasi-3D-study of a section close to the tip region is considered. The passing of the wake of the inlet guide vane over the rotor is studied for six different vibration mode shapes of increasing complexity (first bending mode up to 4th chordwise bending mode).
Whereas for low rotor speeds the comparison between linearized and non-linear calculations is quite good, large differences are found for high rotor speeds. It is shown that an acoustic interaction between the two stages with a cut-on mode is the cause for the large differences, leading to much higher unsteady pressure amplitudes on the rotor blade. This in turn leads to different aerodynamic work on the rotor blade for the different mode shapes.
The extension of the investigations to 3D shows essentially the same effects.