Experimental Study of Turbulent Structures in a Non Isothermal Horizontal Jet Issuing from a Round Nozzle Distanced from a Wall

A non isothermal horizontal jet issuing from a round nozzle distanced from a wall is investigated experimentally. We consider four cases: an isothermal jet, a hot air jet, a cold air jet interacting with the wall and a cold air jet falling down without reaching the wall. The jet expansion rates show two categories. These are (1) an isothermal jet and cold jet not adhering to the wall, with a vertical expansion rate higher than the lateral rate and (2) a non isothermal jet adhering to the wall, with a lateral expansion rate higher than the vertical one. The turbulence structure analysis confirms two categories: the first is a highly anisotropic structure which is mainly cigar axisymmetric and the second one is subject to instabilities linked to lateral air ejections. This is confirmed by a spectral analysis of the turbulent component of the flow. A scenario of coherent structures evolution is proposed.