Turbulent front structure of an axisymmetric compressible wake

Abstract

Intermittency measurements have been performed within the first 100 virtual diameters of an axisymmetric compressible wake. The primary measurements, performed with the hot-wire anemometer, concerned the intermittency factor and the frequency of ‘zero crossings’. The intermittent flow covered most of the wake profile but for a narrow region about the axis, and was found to be normally distributed around the average front position. The latter, along with the extent of the front standard deviation, was found to agree numerically with expectations based on low speed wakes and to grow as the 1/3 power of axial distance. A weak periodicity of the front was detected at a wavelength about nine times greater than the longitudinal scale of turbulent velocity fluctuations. This periodicity affects the turbulent spectra.