Investigation of flow structures of a basic annular jet

A conditional sampling study of the pressure fluctuations in the mixing regions of a basic annual jet is performed to characterize the wake and the structures in the outer shear layer, and the wake structures shed from the recirculating region behind the central body in the inner mixing region together with the wake-induced structures in the outer mixing region are determined from the recovered pressure signals. Results show that some of the initial jet vortices rolled up in the shear layer merge into the wake-induced structures under the excitation of the disturbance due to the shedding of the wake structures from the interface, with wake-induced structures not in toroidal form.