Visualization of Vortex Structures in the Near Field of the Round Jet Formed in Curved Channel by PIV-Method

The results of experimental investigation of the round jet with Dean vortices (Re_d = 4 000, De = 1 673) using Particle Image Velocimetry are presented. The measurements were performed with synchronization the phase of acoustic signal and a laser pulse. Instant picture of vorticity field ωz and vector velocity field for the U- and V-components of the jet cross-actions show Dean vortices near the output of the channel in the low velocity gradient field and Kelvin – Helmholtz vortices in the high-velocity gradient field. The presence of Dean vortices distorts two-dimensional vortex ring, which gets an Ω-shaped form, at that the « head» of Ω-vortex outpaces its «legs», as it is in a higher velocity area.

Keywords:
free round jet, Dean vortices, Kelvin – Helmholtz instability, Particle Image Velocimetry. 
УДК 532.526

Visualization of Vortex Structures in the Near Field of the Round Jet Formed in Curved Channel by PIV-Method