ANALYSIS OF INSTABILITY INCEPTION IN HIGH-SPEED MULTISTAGE AXIAL-FLOWCOMPRESSORS

A nonlinear, two-dimensional, compressible dynamic model has been deve loped to study rotating stall/surge inception and development in high- speed, multistage, axial flow compressors. The flow dynamics are repre sented by the unsteady Euler equations, solved in each interblade row gap and inlet and exit ducts as two-dimensional domains, and in each b lade passage as a one-dimensional domain. The resulting equations are solved on a computational grid. The boundary conditions between domain s are represented by ideal turning coupled with empirical loss and dev iation correlations. Results are presented comparing model simulations to instability inception data of an eleven stage, high-pressure-ratio compressor operating at both part and full power, and the results ana lyzed in the context of a linear modal analysis.