Linear stability analysis applied to flow duct acoustics

Linear stability analysis is applied to configurations based on a T-junction subjected to grazing flow. This setup is a well-known case where flow-acoustic interaction can result in aperture tones provided sufficient acoustic feedback is present. The flow acoustic interaction is characterised as Rayleigh impedances, these together with the acoustic impedance of the attached components result in a total impedance that characterises the system. Stability analysis is then applied to the derived total impedance using a slightly modified version of the Nyquist criterion as known from control theory.