Wake and wake-induced shear-layer excitation in an annular jet

Abstract

The wake and wake‐induced structures in the initial region of an annular jet (with a center body truncated at the jet exit plane) are studied from the measurements of velocity correlation and conditional sampling. Both sets of structures are found to play an important role in momentum transports and Reynolds stress production. They are also found to be oriented in a quasi‐two‐dimensional orderly pattern. In the initial outer shear layer, a large‐scale instability is induced by the shedding of the vortex‐street‐like wake structures from the center body. This wake‐induced instability is associated with the formation of the induced coherent structures and the subsequent zigzag staggered pattern occupied by them and the inner wake structures on the quasi‐two‐dimensional orderly plane.