One-dimensional methods used for solving acoustic instabilities are of doubtful value in the design of afterburner systems. In this paper a three-dimensional method developed and used at Volvo Aero Corporation is described. The method deals with the mean flow and the perturbation flow separately. The perturbation part is based on the linearized Euler equations (time domain) for compressible multi-species flow together with a spectrum trans-formation and Arnoldis method for eigenmode extraction
