RESPONSE OF THE AXISYMMETRIC MIXING LAYER TO SUBHARMONIC FORCING AT DIFFERENT AMPLITUDES.

M. Nallasamy, A. K.M.F. Hussain

Research output: Contribution to conferencePaperpeer-review

Abstract

An initially laminar axisymmetric mixing layer of a large air jet (of 27 cm diameter) has been subjected to high-amplitude forcing at the subharmonic of the natural instability frequency, f//N. The excitation is induced acoustically through an axisymmetric slit at the lip, without inducing bulk excitation of the jet exit flow. Subharmonic (f//N/2) forcing can significantly increase the shear layer width in the initial region but reduces the spread rate in the self-preserving region. On the other hand, forcing at a lower subharmonic frequency (i. e. , f//N/10) is effective in producing a significantly higher spread rate in the self-preserving region. Both the amplification rate of the velocity perturbation at the forcing frequency and its saturation amplitude are found to be distinct functions of the forcing amplitude.

Original languageEnglish
Pages106-116
Number of pages11
StatePublished - 1984

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