Three-dimensional Vortical Structure and Mixing Mechanism of a Circular Jet

Article type: Research Article

Authors: Toyoda, K. | Mori, H.

Affiliations: Department of Mechanical Engineering, Hokkaido Institute of Technology, 7-15-4-1 Maeda, Teine-ku, Sapporo 006-8585, Japan.

Abstract: The three-dimensional vortical structure and the mixing mechanism of a circular water jet were investigated by a flow visualization technique. The jet was excited by axial and azimuthal perturbations to stabilize and enhance axisymmetric and streamwise vortices. A laser fluorescent dye and a laser light sheet were used to visualize the jet. The three-dimensional views of vortical structure were constructed by applying the Taylor hypothesis to the jet cross-sectional images. The views reveal the details of the complicated vortical structure. From the three-dimensional views, the areas of jet-boundary surface were calculated to discuss the jet mixing mechanism. The areas of the unmixed region were also discussed to evaluate the mixing rate on the inside of the jet. The result suggests that the enhancement of axisymmetric and streamwise vortices is very effective to increase mixing.

Keywords: jet, vortical structure, visualization, laser light sheet, mixing

Journal: Journal of Visualization, vol. 4, no. 3, pp. 239-244, 2001