DOI: 10.1615/TSFP8
INVESTIGATION OF THE MIXING LAYER IN A SLIGHTLY UNDEREXPANDED SUPERSONIC JET BY PARTICLE IMAGE VELOCIMETRY
RESUMO
A slightly underexpanded supersonic jet at a Mach number Mj of 1.10 is studied experimentally. Schlieren visualizations and particle image velocimetry are applied in order to characterise the shock-cell structure and turbulence in the mixing layer, which are the two elements at the origin of the shock-associated noise emitted by such a jet. It is found in particular that the velocity gradients typical of the shock-cell structure still exist in the subsonic part of the mixing layer. From the evaluation of some turbulence properties (turbulence level, momentum thickness and spatial correlation), it is shown that the jet behaves very similarly to jets at high subsonic Mach numbers. It is believed that such data could shed light on the shock-associated noise source.