Small-amplitude disturbances in turbomachine flows with swirl

A method is proposed for determining the response of the steady swirling potential flow past a blade row in an axial turbomachine to the most general type of 'nonacoustic' incident disturbance. The method is based on Goldstein's decomposition of the disturbance velocity and only requires solving a linear inhomogeneous wave equation. It is believed that numerical solutions to this wave equation can be obtained more efficiently and will be more accurate than corresponding solutions to the linearized compressible Euler equations.