Explanation of visual diagnostics of multihelix vortex breakdown

摘要

The presence of breakdown for the vortices indicated and for other concentrated vortices is characterized by an abrupt deceleration of the axial velocity at the vortex axis, which sometimes results in the formation of a zone with reversal flow or a recirculation region. The results of visualizations were substantiated by the reconstruction of the three-dimensional structure of the measured velocity field at the same modes where the multihelix breakdowns were visualized. The existence of the multihelix forms of vortex breakdown and the steady multivortex structures can be the starting point for describing the special operating modes of vortex devices, for creating the concept of multicellular cloud formation in the center of intense tropical cyclones, and for simulating a tornado with a multivortex structure of the core.