抄録
Flow visualization and measurements of mean and fluctuating velocities were performed on the coaxial jet with a velocity ratio of 0.6 at a Reynolds number of 3000 in an open water tank using hot-film anemometry, particle image velocimetry (PIV) and laser-induced fluorescence (LIF). The axisymmetric and streamwise vortical structures were revealed in the nearfield of coaxial jet. The annular nozzle has six vortex generators in order to enhance the streamwise vortices generating in the mixing layer. Furthermore, the annular jet was excited by a shaker in order to enhanced the axisymmetric vortices. For the tabbed coaxial jet, the jet spreading was increased than that of the jet without tabs in the downstream. While the axisymmetric and the streamwise vortex structures independently increased jet spreading, a combination of the two diminished the effect. As a result, the turbulent intensity of the tabbed coaxial jet in the inner mixing region is not higher than that of the coaxial jet without tabs.
