Turbulence measurements in subsonic and supersonic axisymmetric jets in a parallel stream

Measurements of mean and fluctuating velocity components have been made in an unheated axisymmetric jet mounted in a low-speed wind tunnel. The measurements were made with a backscatter laser velocimeter. Velocity measurements are presented for jet exit Mach number from 0.47 to 1.67 and tunnel velocity to jet exit velocity ratios from 0.1 to 0.5. The rate of growth of the annular mixing region agreed closely with that of the two-dimensional mixing layer. The potential core length was found to be nearly inversely proportional to the jet exit, freestream velocity difference. Peak axial turbulence intensities varied as the seven-tenths power of the velocity difference. The mean velocity, turbulence intensity and axial velocity skewness, and kurtosis distributions were found to agree with measurements of jets into still air using an appropriate local radial coordinate based on vorticity thickness.