Bow-Shock Instability and its Control in front of Hemispherical Concave Shell at Hypersonic Mach Number 7

抄録

In this study, effectiveness of vortex manipulation by using passive control methods at hypersonic flows have been studied to control the bow-shock instabilities in front of negative curvature (concave) hemispherical shell. The force measurement and unsteady center pressure measurements were performed for hemispherical shell with no control and with three kind of passive controls such as spike at the center of cavity, breathing holes at the curved surface and crosswire along the diameter of hemisphere. The flow visualization for shock instability in front of all four geometries were performed using twin mirror Schlieren system and high-speed camera with 10,000 fps, which were synchronized with pressure measurements. The fluctuations in bow-shock were computed in time resolved manner by image processing methods and compared with pressure data. It is found that drag coefficient does not change significantly by using the different control methods, which were studied. The time resolved Schlieren image processing method is reliable in providing the information of shock fluctuations and the crosswire control method is most effective in subsiding the large shock deformation in the current study.