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 centre body truncated at the jet exit plane) were studied from the measurements of velocity correlation and conditional sampling. Both sets of structures were found to play an important role in momentum transports and Reynolds stress production. They were 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 centre 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. (A)