Visualization of Unsteady Flow near Open-End of Tube Caused by Discharge of Shock Wave

When the shock wave propagating the straight circular tube reaches at the open end, the impulsive wave is generated by the emission of a shock wave from an open end and the unsteady pulse jet is formed near the open end behind the impulsive wave under the specific condition. This paper aims to clear the mechanism of generating the unsteady pulse jet near the open end and the numerical analysis carried out for the emission of propagating the shock wave from an open end of a tube in this study. The flow field is visualized by the computed shadowgraph method using the axisymmetric two-dimensional density distribution contained the axis, which is obtained by the numerical calculation. In this paper, the mechanism of generating the unsteady pulse jet and the characteristics of a pressure distribution in the flow field, the secondary and spherical shock waves behind the impulsive wave are discussed.