Flow instability inception model of compressors based on eigenvalue theory

An eigenvalue theory on flow stability in turbomachinery is proposed with the emphasis on flow instability onset. Based on this theory, a stall inception model including the effects of complex solid geometry is developed for multi-stage fan/compressors system. The capacity of the present model to predict the stall inception point is assessed against experimental data of both low speed and transonic single rotor. Comparisons with a simplified two-dimensional model are performed to identify the nonnegligible effects of spanwise distribution of flow field in a general configuration on the unstable mode of the concerned fan/compressors. It is verified that this model is capable of predicting stall onset point of both subsonic and transonic flow with a relative error of less than 1.8%, and it is sustainable in terms of computation cost for industrial application.