Effect of Scaling of Blade Row Sectors on the Prediction of Aerodynamic Forcing in a Highly Loaded Transonic Compressor Stage

An investigation of the sensitivity of a geometrical scaling technique on the blade forcing prediction and mode excitability has been performed. A stage of a transonic compressor is employed as a test object. A scaling ratio is defined, which indicates the amount of scaling from the original geometry. Different scaling ratios are selected and 3D Navier–Stokes unsteady calculations completed for each scaled configuration. A full-annulus calculation (nonscaled) is performed serving as reference. The quantity of interest is the generalized force, which gives a direct indication of the mode excitability. In order to capture both up- and downstream excitation effects, the mode excitability has been assessed on both rotor and stator blades. The results show that the first harmonic excitation can be predicted well for both up- and downstream excitations using moderate amounts of scaling. On the other hand, the predictions of second harmonic quantities do show a higher sensitivity to scaling for the investigated test case.