In recent years, research and development activities for next generation supersonic transport are being carried out actively by the world aeronautical community. In a supersonic intake, a cavity plays a important role in the control of shock waves. The study of the supersonic internal flow with the cavity is important not only for research on industrial applications but also for basic research in gasdynamics. In the present study, the supersonic internal flow with backward facing steps and cavities were investigated experimentally in the case of the flow Mach number 1.5 at the step and cavity entrance. A schlieren optical system, and a Mach-Zehnder interferometer composed of an Argon laser (CW) as the light source with acoust-optic modurators (AOM) were used to visualize the flow.
