Stability of converging cylindrical shock waves in a vertical annular co-axial diaphragmless shock tube

The motion and stability of converging cylindrical shock waves created in a vertical annular co-axial shock tube and its characteristics were experime ntally studied. To generate converging cylindrical shock waves, a vertical shock tube having a self-sustained structure was constructed. The initiatio n of shock waves was made by the sudden movement of a ring-shaped rubber me mbrane separating high-pressure driver gas from low-pressure test gases. Ri ng-shaped shock waves at a relatively wide range of shock wave Mach numbers were obtained. The characteristics of this shock tube are compared with th ose of a previous horizontal annular co-axial shock tube. For flow visualiz ation, double-exposure holographic interferometry was used. The paper repor ts results of visualization and pressure measurements in this shock tube. C ylindrical shock waves created in this shock tube appear to be more stable than those in the previous one. Good agreement of the motion of converging shock waves between experiments and the ray shock theory was obtained.