The vortex ring state of a rotor and its comparison with the collapse of an annular jet in counterflow

The vortex ring state (VRS) of a rotor is associated with the development trailed system in powered descending flight, where topology wake changes from its usual helical form into toroidal form. In VRS, envelops entire rotor, and it sheds reforms an unsteady manner. previous attempts to understand basic phenomenology focus was on role vortices transition VRS: computational experimental work utilized models generate trailing wake, mechanisms for emergence VRS were postulated based interaction vortices. this paper, different approach taken: set experiments core annular jet flow are described, counterflow used simulate descent. It shown that leads formation field shares many features system. This brings question blade proposed instead between mean drives phenomenon.