Flow structure generated from an axisymmetric natural air jet at a moderate Reynolds number

This paper reports on an experimental study of a free air jet evolving naturally and discharging from a round nozzle at a Reynolds number of 1600. By using flow visualization images and time-series analysis, the details of the flow behavior are clarified. In particular, the length of the transition zone of the jet is measured and its temporal evolution is investigated. We show that the vortex structures interact with each other, thus producing different sizes in the flow. The probability distribution and temporal evolution of the jet width at various distances from the nozzle exit are studied. The occurrence frequency of vortex rings and the Strouhal number of the jet were also determined at different positions from the nozzle exit. The results obtained are compared with those reported in the literature.