音響励起を利用した円形噴流に形成する４個の渦輪の合体過程

抄録

In the initial region of a round jet, there are periodic vortex rings, which merge to form a large-scale vortex ring that subsequently collapses and becomes turbulent. This study focuses on the merging of vortex rings in a round jet, and aims to clarify the conditions for the regular merging of vortex rings. In order to investigate the merging process of vortex rings by acoustic excitation, visualization experiments were conducted to the jet with various Reynolds numbers by applying disturbances. As a result, it is found that there is the range of Strouhal number in which the merging of 4 vortex rings occurs. The reason is discussed and it is found there is suitable distance between vortex rings.