Flow structure and pressure oscillations during the interaction of a supersonic underexpanded gas jet with a tubular cavity

Supersonic jets are widely used in devices based on the phenomenon of a self-oscillating process that occurs when a gas flow interacts with circular cavities (gas-jet sound emitters). The mechanisms of maintaining undamped pressure oscillations and determining the flow field in the tube cavity during the interaction of a supersonic underexpanded jet with cavity are considered. The physical pattern of the flow in the cavity of a gas-jet emitter is discussed, the existence of odd longitudinal modes is shown, and wave diagrams are proposed for describing the flow in odd longitudinal modes. The wave diagrams are based on the analysis of the signals of piezoelectric sensors, recording pressure oscillations in the tube cavity. The calculation of the flow parameters in the tube cavity in longitudinal modes is based on the flow velocity and speed of sound diagram.