THE EXCITED PLANE JET: SPATIAL GROWTH OF VARICOSE OSCILLATIONS

The behavior of a plane jet when acoustically excited was investigated experimentally, in order to obtain a description of jet oscillations in the presence of its symmetrical (varicose) modes. The jet flow was visualized by the Schlieren technique and subsequent image processing was applied, aiming to obtain the parameters necessary to describe the variations of the jet thickness in the region of exponential shear layer growth. Starting from the theoretical analysis regarding the instability of a parallel flow, a semi-empirical model for the space-time evolution of the jet column oscillations was developed, which provides good agreement with the experimental data.