抄録
The interaction of vortex rings and streamwise vortices in an axisymmetric jet is studied by flow visualization and velocity measurement. The jet is excited by axial and azimuthal perturbations to stabilize and enhance axisymmetric and stream-wise vortices. A laser fluorescent dye and a laser light sheet are used to visualize the jet. The three-dimensional views of jet-boundary surface and streamwise vortices are constructed by applying the Taylor hypothesis to the jet cross-sectional images, and the interaction model of axisymmetric and stream-wise vortices is proposed. The characteristics of the flow field and the entrainment of the jet are also discussed in relation to the vortical structure. Moreover, the relation of the vortical structure and the entrainment in the initial region of a plane jet was also investigated with four types of vortex generators by vorticity measurements. The vortices were enhanced and stabilized by streamwise and spanwise disturbances. The three-dimensional views of the vortices were constructed by applying the Taylor hypothesis to the phase-average vorticities, and the entrainment was discussed in relation to the vortical structures. The result reveals the enhancement of entrainment by the interaction of streamwise and spanwise vortices.
