Coherent structures in the mixing zone of a subsonic hot free jet

The existence of a large scale structure of turbulence in a free hot jet is emphasized by measurements carried out on the initial assumption of a fine scale structure. Second order analysis allows one to split the signals picked up in the jet and in the acoustic field into coherent and non-coherent components. The validity of this decomposition with regard to the physical picture of the phenomenon, i.e. vortices convected in the mixing zone, is tested by means of conditional sampling analysis, applied for several diagnostics.