Effects of the shock tube open-end shape on vortex loops released from it

Abstract

In the Interdisciplinary Shock Wave Reach Center, Institute of Fluid Science, Tohoku University, a series of experiments has been conducted aiming to investigate the shockvortex interactions. For the study of vortex ring or loop a special double diaphragm shock tube was designed. Different types of orifices can be attached to the end of this shock tube. In this study, we focus on the vortex ring propagation with different orifices, whose opening diameters and shape are different. In order to observe the vortex ring schlieren method was used. It is found that different shapes or orifices effect the time between the moment when jet captures the vortex and the moment when the vortex completely breaks down. When star shape orifice is used, vortex loop becomes big around its tips and insignificant difference of propagation velocity of the vortex loop between the blunt orifice and the star orifice is observed.