Generation of Large-Scale High-Velocity Vortex Rings by Initiating an Explosive

By initiating explosive charges in a cylindrical tube with one end face being plugged, vortex rings with diameters of the order of 1 m and initial velocity of motion greater than 100 m/s are obtained. Such rings emit a clearly heard acoustic signal, which is of interest for studying generation of acoustic waves by vortices and scaling mechanisms of noise generation. Vortex rings are generated due to exhaustion of a high-velocity gas jet formed after shock wave propagation over the tube. The measured vortex velocities are found to be weakly dependent on the explosive mass, i.e., as the mass increases, the fraction of energy transformed to the vortex ring energy becomes smaller.