Axial transonic compressor flow instability prediction based on eigenvalue theory

Flow instability is a great challenge in turbomachinery, and rotating stall is one major type of flow instability in compression system of aero-engine. In the present paper a rotating stall inception model based on a general eigenvalue theory of flow stability is developed with an emphasis on flow instability onset in axial transonic compressors. After solving the established eigenvalue equation using the spectral method and the singular value decomposition (SVD) method, the onset point of flow instability is determined by the imaginary part of the resultant eigenvalue. The significant effect of flow compressibility on the stall onset point calculation for a transonic rotor is studied by comparing the prediction results for a high speed single rotor at both high and low rotational speeds. The capacity of the present model to predict the stall inception point is assessed against the experimental data of a transonic single stage compressor. It is verified that this model is capable of predicting the mass flow at the stall onset point of a multi-stage transonic compressor flow with reasonable accuracy without numerous empirical data, and it is sustainable in terms of computation cost for industrial application.