An inception criterion of rotating stall in multistage axial flow compressors is derived for the unsteady

two dimensional and incompressible flow model according to the small disturbance stability theory.By means of a three vector equation system

the correlative equations of the undetermined parameters are thus deduced when the small disturbance theory is applied to multiple blade rows.The prediction of the rotating stall onset boundary in the multistage axial flow compressors has been accomplished with the computer program designed by the authors.A theoretical prediction approach is proposed with the aid of the prediction method of stable cascade characteristics.A good agreement between the analytical and experimental results indicates that the theoretical analysis is believable.As compared with the calculation results

the influences of the undetermined parameters

such as stall cells and axial distance between two stages

on the prediction values are discussed.