Analysis of Instability Inception in High-Speed Multistage Axial-Flow Compressors

Abstract

A nonlinear, two-dimensional, compressible dynamic model has been developed to study rotating stall/surge inception and development in high-speed, multistage, axial flow compressors. The flow dynamics are represented by the unsteady Euler equations, solved in each interblade row gap and inlet and exit ducts as two-dimensional domains, and in each blade passage as a one-dimensional domain. The resulting equations are solved on a computational grid. The boundary conditions between domains are represented by ideal turning coupled with empirical loss and deviation 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 analyzed in the context of a linear modal analysis.