Self-sustained oscillations of a circular gas jet

Self-sustained oscillations of a jet flowing out of an annular orifice in an impedance plane into an unconfined space and impinging on another plane or an obstacle of, for example, annular shape, are analyzed. This arrangement forms a source of volumetric flow rate in the deflection region of the jet, which may result in excitation of axial acoustic waves. By using the Nyquist stability criterion, conditions favoring the onset of self-sustained oscillations are found, and their dependence on the parameters of the problem is determined.