抄録
Coaxial jets have been experimentally studied, and both the outer annular jet and the inner circular jet are excited by the sound wave from speakers with controlled initial phase differences. We have measured velocity and turbulent intensity distributions of the excited coaxial jets with the velocity ratio of 0.6 and the forcing frequency of 333Hz, which is a half of natural vortex frequency. It is found that the intensity of fluctuating velocity in the outer mixing region for the excited outer jet increases than the excited inner jet, and the excitation of the outer jet is indeed more effective than the other excitation in the jet mixing enhancement. For the excited both jets, the excitation of the phase difference φ=0° produces large-scale structures in the shear-layers, and the intensity of fluctuating velocity in the both mixing regions increases. It is shown that the excitation of the phase difference φ=260° can reduce the turbulence intensities in the mixing regions than the excitation of the other phase difference.
