超音速噴流の流れ場の音響解析

抄録

An underexpanded jet is one of supersonic jets. The jet becomes underexpanded when the pressure ratio exceeds the critical value across the convergent nozzle discharging it. The jet is not uniform because of the presence of the expansion wave, the compression wave and the shock wave formed in it. In the jet boundary, many vortices are generated by the shearing stress between the supersonic flow of jet and still atmosphere The interaction of vortices and jet is closely related to the strong acoustic noise radiating from such flow field. In this study, the acoustic characteristic of flow field of underexpanded jet was experimentally examined. The flow field was visualized using shadowgraph methods. And the acoustic noise emitted from the flow field is measured using a microphone.