Effects of nonparallel exit flow on round turbulent free jets

Abstract Results of an experimental and numerical study of the effects of nonparallel exit flow on round turbulent free jets are presented. Two nozzle types with the same exit area were used: a sharp-edged slot machined into an aluminum plate and a smoothly contoured nozzle manufactured from Plexiglass. Hot-wire anemometry was used to obtain the mean acquired with a pitot-static tube and a pressure transducer. An elliptic, finite-volume-based procedure was used in the numerical study which predicted the mean velocity and the mean static pressure. The experimental results show the existence of distinct off-center peaks in the mean streamwise velocity in the very near flow field of the jet from the sharp-edged round slot, which had pronounced nonparallel exit flow. These mean streamwise velocity off-center peaks were absent in the smoothly contoured nozzle jet flow which was found to spread faster than the sharp-edged slot jet flow in the initial region. The agreement between the experimental results and the numerical predictions was found to be excellent for the mean streamwise velocity decay on the jet centerline and the spread of the jet beyond the initial region. Only qualitative agreement can be claimed for the other quantities.