On mixing in an elliptic turbulent free jet

This paper documents the results of an experimental study of the mean flow and turbulence characteristics of a turbulent free jet of air issuing, into still air surroundings, from a sharp-edged elliptical slot of aspect ratio 5. The measured quantities, which were obtained with hot-wire anemometry as a flow diagnostic tool, include the mean streamwise velocity, the turbulence intensities, the Reynolds shear stress, the transport of some of the Reynolds stresses, and the flatness and skewness of the distributions of the streamwise velocity fluctuations. Two switches of the major and minor axes were observed and it was found that the jet attains an axisymmetric shape at about 30 equivalent slot diameters downstream of the exit plane. Also, the jet, compared to a turbulent free jet from a sharp-edged round slot of the same exit area, was found to entrain ambient fluid faster both in the near and far flow fields.